Sync in both directions with Rsync

I have two directories and I want to make sure they are both in sync with the latest files in each:

./site/app/Library
./api/app/Library

Sync:

rsync -rtuv ./site/app/Library ./api/app
rsync -rtuv ./api/app/Library ./site/app

Use --dry-run (-n) for testing

note this won't handle deletions :(