chore(Makefile): make test-promise filter more strict + update docs

Make the promise test suite filter that skips invalid tests more strict to prevent
accidental test exclusion.

Also add a better explanation of why the sloppy (non-strict mode) tests are being skipped.
Merge pull request #930 from IgorMinar/aplus-promise-fix

chore(Makefile): make test-promise filter more strict + update docs