Move relay docs to a separate file

docs/administration/CLI_tasks/relay.md

@@ -0,0 +1,30 @@
+# Managing relays
+
+Every command should be ran with a prefix, in case of OTP releases it is `./bin/pleroma_ctl relay` and in case of source installs it's `mix pleroma.relay`.
+
+## Follow a relay
+```sh
+$PREFIX follow <relay_url>
+```
+
+Example:
+```sh
+$PREFIX follow https://example.org/relay
+```
+
+## Unfollow a remote relay
+
+```sh
+$PREFIX unfollow <relay_url>
+```
+
+Example:
+```sh
+$PREFIX unfollow https://example.org/relay
+```
+
+## List relay subscriptions
+
+```sh
+$PREFIX list
+```