doc: Add docs on release failure chat notifications (google-gemini#8768)

Author: bobcatfish

docs/releases.md

@@ -397,3 +397,26 @@ graph TD
 
 This process ensures that the final published artifact is a purpose-built, clean, and efficient representation of the
 project, rather than a direct copy of the development workspace.
+
+## Notifications
+
+Failing release workflows will automatically create an issue with the label
+`release-failure`.
+
+A notification will be posted to the maintainer's chat channel when issues with
+this type are created.
+
+### Modifying chat notifications
+
+Notifications use [GitHub for Google Chat](https://workspace.google.com/marketplace/app/github_for_google_chat/536184076190). To modify the notifications, use `/github-settings` within the chat space.
+
+> [!WARNING]
+> The following instructions describe a fragile workaround that depends on the internal structure of the chat application's UI. It is likely to break with future updates.
+
+The list of available labels is not currently populated correctly. If you want to add a label that does not appear alphabetically in the first 30 labels in the repo, you must use your browser's developer tools to manually modify the UI:
+
+1. Open your browser's developer tools (e.g., Chrome DevTools).
+2. In the `/github-settings` dialog, inspect the list of labels.
+3. Locate one of the `<li>` elements representing a label.
+4. In the HTML, modify the `data-option-value` attribute of that `<li>` element to the desired label name (e.g., `release-failure`).
+5. Click on your modified label in the UI to select it, then save your settings.