./script/trigger-release (#10589)

Add `./script/trigger-release {nightly|stable|preview}`

This command can be run regardless of the state of your local git
repository, and it
either triggers a workflow run of `bump_patch_version.yml` (for
stable/preview) or
it force pushes the nightly tag.

Also add some docs on releases to explain all of this.

Release Notes:

- N/A

script/get-released-version

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+channel="$1"
+
+query=""
+case $channel in
+  stable)
+    ;;
+  preview)
+    query="&preview=1"
+    ;;
+  nightly)
+    query="&nightly=1"
+    ;;
+  *)
+    echo "this must be run on either of stable|preview|nightly release branches" >&2
+    exit 1
+    ;;
+esac
+
+curl -s https://zed.dev/api/releases/latest?asset=Zed.dmg$query | jq -r .version