Fix broken links to source examples (#501)
Fix broken links to source examples (#501)

* Fix broken links to source examples

`transform.sql` and `schema.json` links were broken, fixed to go to correct files now.

* Update README.md

Co-authored-by: mservidio <b869c2c480b833ffdb40842145c01d74d203fbf2@google.com>
GoogleCloudPlatform/datashare-toolkit,GoogleCloudPlatform/datashare-toolkit,GoogleCloudPlatform/datashare-toolkit,GoogleCloudPlatform/datashare-toolkit,GoogleCloudPlatform/datashare-toolkit