ci: Update documentation trigger to main branch

The deployment workflow was still targeting 'master', which prevented automatic documentation updates after the branch rename.

Co-authored-by: Gemini CLI <noreply@google.com>

Author: kakra

.github/workflows/pages.yml

@@ -3,7 +3,7 @@ name: Deploy Documentation
 on:
   push:
     branches:
-      - master
+      - main
     paths:
       - 'docs/**'
       - README.md