docs: Describe support links (#6353)

* docs: Describe support links

* Fix: size

* Address PR comments

docs/admin/support-links.md

@@ -0,0 +1,28 @@
+# Support Links
+
+Support links let admins adjust the user dropdown menu to include links referring to internal company resources. The menu section replaces the original menu positions: documentation, report a bug to GitHub, or join the Discord server.
+
+![support links](../images/admin/support-links.png)
+
+Custom links can be set in the deployment configuration using the `server.yaml` file:
+
+```yaml
+support:
+  links:
+    - name: "On-call 🔥"
+      target: "http://on-call.example.internal"
+      icon: "bug"
+    - name: "😉 Getting started with Go!"
+      target: "https://go.dev/"
+    - name: "Community"
+      target: "https://github.com/coder/coder"
+      icon: "chat"
+```
+
+## Icons
+
+The link icons are optional, and limited to: `bug`, `chat`, and `docs`.
+
+## Up next
+
+- [Enterprise](../enterprise.md)