You wouldn’t use it on your git tagown since it created a light tag (link to the tag for the name of the SHA-1 object of the commit object).
In the case of angular / angular-phonecat, they use:
git tag -m "step-2 angular template with repeater" step2
Adding a comment is enough to make it annotated tags ; they contain the creation date, tagger name and email, tag message, and optional GnuPG signature.
, step2 - ().