docs: use Haystack Bot in Docusaurus sync (#9884)

Author: anakin87

.github/workflows/docusaurus_sync.yml

@@ -48,7 +48,7 @@ jobs:
 
       - name: Commit and push changes
         env:
-            GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+            GITHUB_TOKEN: ${{ secrets.HAYSTACK_BOT_TOKEN }}
         run: |
           git config --global user.name "github-actions[bot]"
           git config --global user.email "github-actions[bot]@users.noreply.github.com"