* Update samples for "vela show xxx --web"

Also stop generating components/traits docs under
docs/en/end-user and remove the command from Makefile

Fix #1602

* fix doc build issue

* Update references/plugins/references.go
Co-authored-by: Jianbo Sun <wonderflow.sun@gmail.com>

* Enhance --web feature for "vela show"

- Find the capability in "vela-system" if notfound in the current ns
- Don't depend on local capabilities

* add ut for GetCapabilityByName in references/plugins/cluster.go

* add ut for GetNamespacedCapabilitiesFromCluster in references/plugins/cluster.go

* add ut for GenerateTerraformCapabilityProperties in references/plugins/references.go

* fix import issue
Co-authored-by: Jianbo Sun <wonderflow.sun@gmail.com>