docs-builder: add pull-requests: write permission to docs-build workflow (elastic#129779)

Co-authored-by: shainaraskas <[email protected]>

Author: 2 people

.github/workflows/docs-build.yml

@@ -16,4 +16,4 @@ jobs:
       deployments: write
       id-token: write
       contents: read
-      pull-requests: read
+      pull-requests: write