doc: indicate that abort tests do not generate core files
The key thing about the tests in test/abort is that tests in that
directory do not generate core files (thanks to testcfg.py). Make a note
of that in the test README.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The key thing about the tests in test/abort is that tests in that
directory do not generate core files (thanks to testcfg.py). Make a note
of that in the test README.