update(ci): enable manual trigger for build/publish doc (#338)

.github/workflows/documentation.yml

@@ -5,21 +5,26 @@ name: "📚 Documentation"
 # events but only for the master branch
 on:
   push:
-    branches: [main]
+    branches:
+      - main
     paths:
       - "docs/**"
       - "*.md"
       - ".github/workflows/documentation.yml"
+      - ./mkdocs_rss_plugin
     tags:
       - "*"
 
   pull_request:
-    branches: [main]
+    branches:
+      - main
     paths:
       - .github/workflows/documentation.yml
       - docs/
       - requirements/documentation.txt
 
+  workflow_dispatch:
+
 # Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
 permissions:
   contents: read