in help text for 'binary' goal, don't say "jar". Nowadays, could be a pex.

So be vague.

Testing Done:
Just in case: https://travis-ci.org/pantsbuild/pants/builds/44236259

Bugs closed: 782

Reviewed at https://rbcommons.com/s/twitter/r/1491/
Sync of https://github.com/pantsbuild/pants/commit/a5032f51470644deb6ed3f0f2bb713f36e82e35f