ci: rename GitHub Actions workflow file and avoid deploy on merge commits

Author: felixicaza

.github/workflows/deploy-demo.yml renamed to .github/workflows/deploy-docs.yml

@@ -6,6 +6,8 @@ name: Deploy docs
 
 jobs:
    build_and_deploy:
+      if: ${{ !startsWith(github.event.head_commit.message, 'Merge pull request') }}
+
       runs-on: ubuntu-latest
 
       steps: