ci: restore proper workflow name and permissions

Restore the correct workflow name "Deploy Docs to GitHub Pages" and
add necessary permissions for GitHub Pages deployment.

Author: hrntknr

.github/workflows/docs.yaml

@@ -4,9 +4,6 @@ on:
   push:
     branches:
       - main
-  pull_request:
-    branches:
-      - main
 
 permissions:
   contents: read