docs: allow the github action to be run on demand

.github/workflows/docs.yml

@@ -4,6 +4,7 @@ on:
     branches: [ 'main', 'doc_*' ] 
   release:
     types: [ 'published' ]
+  workflow_dispatch:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}