Improve GitHub Actions documentation update workflow authentication

- Use 'x-access-token:' prefix for PAT token authentication
- Consolidate clone and push steps into a single named step
- Enhance security and clarity of Git authentication process

Author: Chivier

.github/workflows/update_docs.yml

@@ -26,13 +26,14 @@ jobs:
           cd ..
           sh build_html.sh
       - run: cd ..
-      - run: |
-          git clone https://${{ secrets.PAT_TOKEN }}@github.com/openmlsys/html-en.git
-      - run: cp -r _build/html/* html-en/
-      - run: |
+      # Modified these steps for proper authentication
+      - name: Clone and push to html-en
+        run: |
+          git clone https://x-access-token:${{ secrets.PAT_TOKEN }}@github.com/openmlsys/html-en.git
+          cp -r _build/html/* html-en/
           cd html-en
           git config user.name "Chivier"
           git config user.email "[email protected]"
           git add .
           git commit -m 'update docs'
-          git push https://${{ secrets.PAT_TOKEN }}@github.com/openmlsys/html-en.git main
+          git push https://x-access-token:${{ secrets.PAT_TOKEN }}@github.com/openmlsys/html-en.git main