adding CNAME file to build output for custom docs domain

This PR adds CNAME file to the build artifact via the workflow, allowing GitHub Pages to serve the documentation from the new, shorter URL.

Author: panyamkeerthana

.github/workflows/sphinx-deploy.yml

@@ -29,6 +29,9 @@ jobs:
         run: |
           sphinx-build -W -b html docs/ build
 
+      - name: Create CNAME file
+        run: echo "docs.granitecode.ai" > build/CNAME
+
       - name: Upload documentation artifact
         uses: actions/upload-pages-artifact@v3
         with: