docs(workflow): 记录 Actions 外部依赖约束 (#24)

.gitea/workflows/validate-changelog-filenames.yml

@@ -19,6 +19,7 @@ jobs:
     name: validate
     runs-on: ubuntu-latest
     steps:
+      # Keep the gate self-contained: the test environment cannot reliably clone GitHub Actions repositories.
       - name: Checkout full history
         run: |
           git init -q .