remove unused dist/ directory

The `dist/` directory is unmaintained and gets out of sync with the Linux
packages that we distribute and the documentation found in the Learn
Guides. We even have upstart files for a distro that is out of support!
Remove this directory so that users are not confused.

dist/README.md

-# Dist
-
-The `dist` folder contains sample configs for various platforms.
-
-## Conventions
-
-On unixes we will place agent configs under `/etc/nomad.d` and store
-data under `/var/lib/nomad/`. You will need to create both of these
-directories. We assume that `nomad` is installed to
-`/usr/local/bin/nomad`.
-
-## Agent Configs
-
-The following example configuration files are provided:
-
-- `server.hcl`
-- `client.hcl`
-
-Place one of these under `/etc/nomad.d` depending on the node's
-role. You should use `server.hcl` to configure a node as a server
-(which is responsible for scheduling) or `client.hcl` to configure a
-node as a client (which is responsible for running workloads).
-
-Read <https://nomadproject.io/docs/agent/configuration/index.html> to
-learn which options are available and how to configure them.
-
-## Systemd
-
-On systems using systemd the basic systemd unit file under
-`systemd/nomad.service` starts and stops the nomad agent. Place it
-under `/etc/systemd/system/nomad.service`.
-
-You can control Nomad with `systemctl start|stop|restart nomad`.
-
-The `system/nomad.service` unit file is compatible with systemd v230
-or higher.
-
-## Upstart
-
-On systems using upstart the basic upstart file under
-`upstart/nomad.conf` starts and stops the nomad agent. Place it under
-`/etc/init/nomad.conf`.
-
-You can control Nomad with `start|stop|restart nomad`.

dist/client.hcl

-bind_addr = "127.0.0.1"
-
-data_dir = "/var/lib/nomad/"
-
-client {
-  enabled = true
-  servers = ["10.1.0.1", "10.1.0.2", "10.1.0.3"]
-}

dist/server.hcl

-bind_addr = "0.0.0.0"
-
-data_dir = "/var/lib/nomad"
-
-advertise {
-  # This should be the IP of THIS MACHINE and must be routable by every node
-  # in your cluster
-  rpc = "1.2.3.4:4647"
-}
-
-server {
-  enabled          = true
-  bootstrap_expect = 3
-}

dist/systemd/nomad.service

-[Unit]
-Description=Nomad
-Documentation=https://nomadproject.io/docs/
-Wants=network-online.target
-After=network-online.target
-
-# When using Nomad with Consul it is not necessary to start Consul first. These
-# lines start Consul before Nomad as an optimization to avoid Nomad logging
-# that Consul is unavailable at startup.
-#Wants=consul.service
-#After=consul.service
-
-[Service]
-EnvironmentFile=/etc/nomad.d/nomad.env
-ExecReload=/bin/kill -HUP $MAINPID
-ExecStart=/usr/bin/nomad agent -config /etc/nomad.d
-KillMode=process
-KillSignal=SIGINT
-LimitNOFILE=65536
-LimitNPROC=infinity
-Restart=on-failure
-RestartSec=2
-StartLimitBurst=3
-StartLimitInterval=10
-TasksMax=infinity
-OOMScoreAdjust=-1000
-
-[Install]
-WantedBy=multi-user.target

dist/upstart/nomad.conf

-start on (filesystem and net-device-up IFACE=lo)
-stop on runlevel [!2345]
-
-exec /usr/local/bin/nomad agent -config /etc/nomad.d