Add Peng and Shreya as default reviewers to the auto-doc cleanup PRs (#337)

I've realized that these have kind of been going to a black hole at the
moment.

Author: jklein24

.github/workflows/docs-sync.yml

@@ -151,6 +151,7 @@ jobs:
                - Branch name: `docs/sync-$(date +%Y%m%d)`
                - Clear title describing the sync
                - Description listing what was updated and why, organized by area (docs, Kotlin sample, Grid Visualizer)
+               - Add reviewers: `gh pr edit --add-reviewer shreyav,pengying`
 
             If everything is already up to date:
             - Output a brief summary confirming no updates needed