Update documentation for Reminder.parse.
Update documentation for Reminder.parse.

Indicate that this method doesn't validate the MAC and that the
PasswordGenerator.parse_reminder method should be used instead.

Signed-off-by: brian m. carlson <738bdd359be778fee9f0fc4e2934ad72f436ceda@crustytoothpaste.net>

bk2204/daniel-ruby,bk2204/daniel-ruby