Workflow cleanup.

.github/workflows/cpp-packaging.yml

@@ -655,6 +655,12 @@ jobs:
  run: |
  echo "USE_EXPANDED_MATRIX=1" >> $GITHUB_ENV
  - name: Generate token for GitHub API
+ # This step is necessary because the existing GITHUB_TOKEN cannot be used inside one workflow to trigger another.
+ # 
+ # Instead, generate a new token here, using our GitHub App's private key and App ID (saved as Secrets).
+ # 
+ # This method is preferred over the "personal access token" solution, as the GitHub App's scope is limited to just
+ # the firebase-cpp-sdk repository.
  uses: tibdex/github-app-token@v1
  id: generate-token
  with: