`(pkg-name | service-name): (from -> to | init at version | refactor | etc)`
Examples:
* nginx: init at 2.0.1
* firefox: 3.0 -> 3.1.1
* hydra service: add bazBaz option
* nginx service: refactor config generation
* Don't put dots at the end of package descriptions.
See the nixpkgs manual for more details on how to [Submit changes to nixpkgs](http://hydra.nixos.org/job/nixpkgs/trunk/manual/latest/download-by-type/doc/manual#chap-submitting-changes).