[reminder] please include the category/portname in your ports PRs

[Mark Linimon]

With nearly 20,000 ports, it is becoming harder and harder to guess
which port a particular PR applies to.  Please don't assume that those
reading your PR will be able to tell by quickly glancing at the PR.

Also, if you do include it, the automatic notifier is able to either send
mail, or assign the PR (depending on whether the maintainer is or is not
a committer), and that means there is one less manual step that has to
happen before your PR is processed.

Thanks.

mcl