fix(ci): add contents:read permission to Docs workflow

The explicit permissions block omitted contents:read, causing
actions/checkout to fail on the private repo with "not found".

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Johnson-Ogundeji

.github/workflows/docs.yml

@@ -3,6 +3,7 @@ on:
   push:
     branches: [main]
 permissions:
+  contents: read
   pages: write
   id-token: write
 concurrency: