add generation of help in GHA

Author: SamGuay

.github/workflows/publish_doc.yaml

@@ -47,6 +47,9 @@ jobs:
         run: |
           python3 -m pip install -r ./requirements-doc.txt
           pip install -e .
+          dcm2bids -h > docs_helper/help.txt
+          dcm2bids_helper -h > docs_helper/helper.txt
+          dcm2bids_scaffold -h > docs_helper/help_scaffold.txt
 
       - name: Set git credentials
         run: |