docs: note push-to-repo classic PAT workflow scope requirement (#3511)

* docs: note `push-to-repo` classic PAT `workflow` scope requirement

Closes #3510

* clarify when workflow scope is necessary

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Co-authored-by: Peter Evans <[email protected]>

Author: scop

docs/concepts-guidelines.md

@@ -231,7 +231,7 @@ It will use their own fork to push code and create the pull request.
 
 1. Create a new GitHub user and login.
 2. Fork the repository that you will be creating pull requests in.
-3. Create a Classic [Personal Access Token (PAT)](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) with `repo` scope.
+3. Create a Classic [Personal Access Token (PAT)](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) with `repo` scope. If the upstream repository uses GitHub Actions, it's highly likely that you will also need the `workflow` scope.
 4. Logout and log back into your main user account.
 5. Add a secret to your repository containing the above PAT.
 6. As shown in the following example workflow, set the `push-to-fork` input to the full repository name of the fork.