Backport of docs: add known issues section to 1.9.x upgrade guide into release/1.9.x (#13713)

* no-op commit due to failed cherry-picking

* [VAULT-3252] Add entity-alias behavior change to docs (#13370)

* Add entity-alias behavior change to docs

* Add upgrade note about entity-alias mapping change

* Rename 1.7-9 upgrade pages, shuffle upgrade note position

* Update website/content/partials/entity-alias-mapping.mdx
Co-authored-by: Meggie <meggie@hashicorp.com>

* Add incorrect policy issue to the docs

* Add example about entity-alias restriction
Co-authored-by: Meggie <meggie@hashicorp.com>

* Update http requests API link to versioned docs (#13692)

* docs: add known issues section to 1.9.x upgrade guide (#13662)

* docs: add known issues section to 1.9.x upgrade guide

* minor rephrasing on oidc known issue

* use relative references for URLs

* Update website/content/docs/upgrading/upgrade-to-1.9.x.mdx
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>

* update known issues section for id token
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>
Co-authored-by: temp <temp@hashicorp.com>
Co-authored-by: Pratyoy Mukhopadhyay <35388175+pmmukh@users.noreply.github.com>
Co-authored-by: Meggie <meggie@hashicorp.com>
Co-authored-by: Tony Pulickal <ttp@hashicorp.com>
Co-authored-by: Calvin Leung Huang <1883212+calvn@users.noreply.github.com>
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>

website/content/docs/concepts/identity.mdx

@@ -20,11 +20,13 @@ Each user may have multiple accounts with various identity providers, and Vault
 supports many of those providers to authenticate with Vault. Vault Identity can
 tie authentications from various auth methods to a single representation. This representation of a consolidated identity is called an **Entity** and their
 corresponding accounts with authentication providers can be mapped as
-**Aliases**. In essence, each entity is made up of zero or more aliases. 
+**Aliases**. In essence, each entity is made up of zero or more aliases. An entity cannot have more than one alias for
+a particular authentication backend.
 
 For example, a user with accounts in both GitHub and LDAP can be mapped to a
 single entity in Vault with two aliases, one of type GitHub and one of type
-LDAP.
+LDAP. Note however, if both aliases are created on the same auth mount, say
+a Github mount, both aliases cannot be mapped to the same entity.
 
 ![Entity  overview](/img/vault-identity-doc-1.png)
 

website/content/docs/upgrading/upgrade-to-1.7.0.mdx → website/content/docs/upgrading/upgrade-to-1.7.x.mdx

 ---
 layout: docs
-page_title: Upgrading to Vault 1.7.0 - Guides
+page_title: Upgrading to Vault 1.7.x - Guides
 description: |-
   This page contains the list of deprecations and important or breaking changes
-  for Vault 1.7.0. Please read it carefully.
+  for Vault 1.7.x. Please read it carefully.
 ---
 
 # Overview
 
 This page contains the list of deprecations and important or breaking changes
-for Vault 1.7.0 compared to 1.6. Please read it carefully.
+for Vault 1.7.x compared to 1.6. Please read it carefully.
 
 ## Barrier Key Auto-Rotation
 
@@ -31,6 +31,8 @@ endpoint changes is available in the [AWS Auth API docs](/api-docs/auth/aws#depr
 
 @include 'alpine-314.mdx'
 
+@include 'entity-alias-mapping.mdx'
+
 ## Known Issues
 
 Due to the known issue, Transform Secrets Engine users are recommended to upgrade to version 1.7.0.
@@ -48,3 +50,4 @@ Due to the known issue, Lease Count Quota users with DR Secondaries are recommen
 @include 'transform-upgrade.mdx'
 
 @include 'lease-count-quota-upgrade.mdx'
+

website/content/docs/upgrading/upgrade-to-1.8.0.mdx → website/content/docs/upgrading/upgrade-to-1.8.x.mdx

 ---
 layout: docs
-page_title: Upgrading to Vault 1.8.0 - Guides
+page_title: Upgrading to Vault 1.8.x - Guides
 description: |-
   This page contains the list of deprecations and important or breaking changes
-  for Vault 1.8.0. Please read it carefully.
+  for Vault 1.8.x. Please read it carefully.
 ---
 
 # Overview
 
 This page contains the list of deprecations and important or breaking changes
-for Vault 1.8.0 compared to 1.7. Please read it carefully.
+for Vault 1.8.x compared to 1.7. Please read it carefully.
 
 ## License Enhancements
 
@@ -40,6 +40,9 @@ Notes](https://golang.org/doc/go1.16) for full details. Of particular note:
 
 @include 'alpine-314.mdx'
 
+
+@include 'entity-alias-mapping.mdx'
+
 ## Known Issues
 
 - Vault Enterprise binaries for `arm64` architectures will crash immediately when using production-ready storage backends.  This issue is addressed in Vault 1.8.1.

website/content/docs/upgrading/upgrade-to-1.9.0.mdx → website/content/docs/upgrading/upgrade-to-1.9.x.mdx

 ---
 layout: docs
-page_title: Upgrading to Vault 1.9.0 - Guides
+page_title: Upgrading to Vault 1.9.x - Guides
 description: |-
   This page contains the list of deprecations and important or breaking changes
-  for Vault 1.9.0. Please read it carefully.
+  for Vault 1.9.x. Please read it carefully.
 ---
 
-~> Note: these are **draft** notes for a future version of Vault. They should not be considered
-official guidance until the release has been completed.
-
 # Overview
 
 This page contains the list of deprecations and important or breaking changes
-for Vault 1.9.0 compared to 1.8. Please read it carefully.
+for Vault 1.9.x compared to 1.8. Please read it carefully.
+
+## OIDC Provider
+
+Vault 1.9.0 introduced the ability for Vault to be an OpenID Connect (OIDC) identity
+provider. To support the feature, Vault's [default policy](https://www.vaultproject.io/docs/concepts/policies#default-policy)
+was modified to include an ACL rule for its Authorization Endpoint. Due to the handling
+of Vault's default policy during upgrades, existing deployments of Vault that are upgraded
+to 1.9.0 will not have this required ACL rule.
+
+If you're upgrading to 1.9.0 and want to use the new OIDC provider feature, the following
+ACL rule must be added to the default policy **or** a policy associated with the Vault
+[Auth Method](https://www.vaultproject.io/docs/auth) used to authenticate end-users during
+the OIDC flow.
+
+```hcl
+# Allow a token to make requests to the Authorization Endpoint for OIDC providers.
+path "identity/oidc/provider/+/authorize" {
+  capabilities = ["read", "update"]
+}
+```
 
 ## Identity Tokens
 
@@ -39,13 +56,57 @@ To re-enable the old behavior, update the roles with a value
 of `"*"` to the `allowed_extensions` parameter allowing any/all extensions to be
 specified by clients.
 
-## HTTP Request Counter Deprecation
+@include 'entity-alias-mapping.mdx'
+
+## Deprecations
+
+### HTTP Request Counter Deprecation
 
 In Vault 1.9, the internal HTTP Request count
-[API](https://www.vaultproject.io/api-docs/system/internal-counters#http-requests)
+[API](https://www.vaultproject.io/api-docs/v1.8.x/system/internal-counters#http-requests)
 will be removed from the product. Calls to the endpoint will result in a 404
 error with a message stating that `functionality on this path has been removed`.
 
 Vault does not make backwards compatible guarantees on internal APIs (those
 prefaced with `sys/internal`). They are subject to change and may disappear
 without notice.
+
+### Etcd v2
+
+Support for Etcd v2 will be removed from Vault in Vault 1.10 (not this Vault
+release, but the next one). The Etcd v2 API
+was deprecated with the release of [Etcd
+v3.5](https://etcd.io/blog/2021/announcing-etcd-3.5/), and will be
+decommissioned in the Etcd v3.6 release.
+
+Users upgrading to Vault 1.9 and planning to eventually upgrade to Vault 1.10
+should prepare to [migrate](/docs/commands/operator/migrate) Vault storage to
+an Etcd v3 cluster prior to upgrading to Vault 1.10. All storage migrations
+should have [backups](/docs/concepts/storage#backing-up-vault-s-persisted-data)
+taken prior to migration.
+
+## TLS Cipher Suites Changes
+
+In Vault 1.9, due to changes in Go 1.17, the `tls_prefer_server_cipher_suites`
+TCP configuration parameter has been deprecated and its value will be ignored.
+
+Additionally, Go has begun doing automated cipher suite ordering and no longer
+respects the order of suites given in `tls_cipher_suites`.
+
+See [this blog post](https://go.dev/blog/tls-cipher-suites) for more information.
+
+## Known Issues
+
+### Identity Token Backend Key Rotations
+
+Existing Vault installations that use the [Identity Token
+backend](/api-docs/secret/identity/tokens) and have [named
+keys](/api-docs/secret/identity/tokens#create-a-named-key) generated will
+encounter a panic when any of those existing keys pass their
+`rotation_period`. This issue affects Vault 1.9.0, and is fixed in Vault 1.9.1.
+Users should upgrade directly to 1.9.1 or above in order to avoid this panic.
+
+If a panic is encountered after an upgrade to Vault 1.9.0, the named key will be
+corrupted on storage and become unusable. In this case, the key will need to be
+deleted and re-created. A fix to fully mitigate this panic will be addressed on
+Vault 1.9.3.

website/content/partials/entity-alias-mapping.mdx

+## Entity Alias mapping
+
+Previously, an entity in Vault could be mapped to multiple entity aliases on the same authentication backend. This
+led to a potential security vulnerability (CVE-2021-43998), as ACL policies templated with alias information would match the first
+alias created. Thus, tokens created from all aliases of the entity, will have access to the paths containing alias 
+metadata of the first alias due to templated policies being incorrectly applied. As a result, the mapping behavior was updated 
+such that an entity can only have one alias per authentication backend. This change exists in Vault 1.9.0+, 1.8.5+ and 1.7.6+.
\ No newline at end of file

website/data/docs-nav-data.json

@@ -1437,17 +1437,17 @@
         "path": "upgrading/plugins"
       },
       {
-        "title": "Upgrade to 1.9.0",
-        "path": "upgrading/upgrade-to-1.9.0",
+        "title": "Upgrade to 1.9.x",
+        "path": "upgrading/upgrade-to-1.9.x",
         "hidden": true
       },
       {
-        "title": "Upgrade to 1.8.0",
-        "path": "upgrading/upgrade-to-1.8.0"
+        "title": "Upgrade to 1.8.x",
+        "path": "upgrading/upgrade-to-1.8.x"
       },
       {
-        "title": "Upgrade to 1.7.0",
-        "path": "upgrading/upgrade-to-1.7.0"
+        "title": "Upgrade to 1.7.x",
+        "path": "upgrading/upgrade-to-1.7.x"
       },
       {
         "title": "Upgrade to 1.6.3",