docs: add "permissions.content: write" to GH workflow examples (#8877)

Co-authored-by: Sébastien Lorber <slorber@users.noreply.github.com>

website/docs/deployment.mdx

@@ -390,6 +390,9 @@ on:
     # Review gh actions docs if you want to further define triggers, paths, etc
     # https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#on
 
+permissions:
+  contents: write
+
 jobs:
   deploy:
     name: Deploy to GitHub Pages
@@ -488,6 +491,9 @@ on:
   push:
     branches: [main]
 
+permissions:
+  contents: write
+
 jobs:
   test-deploy:
     if: github.event_name != 'push'