Adding FAQ

Author: cmungall

README.md

@@ -97,3 +97,16 @@ CBORG_API_KEY
 After setting up env vars:
 
 `just -f ai.just setup-ai`
+
+# FAQ
+
+## `claude-review.yml` fails PR check on first run
+
+This is normal: see this comment in the action logs:
+
+```
+Error: Failed to setup GitHub token: Error: Workflow validation failed. The workflow file must exist and have identical content to the version on the repository's default branch. If you're seeing this on a PR when you first add a code review workflow file to your repository, this is normal and you should ignore this error.
+
+If you instead wish to use this action with a custom GitHub token or custom GitHub app, provide a `github_token` in the `uses` section of the app in your workflow yml file.
+Error: Process completed with exit code 1.
+```