CONTRIBUTING: Reference release notes in package bumps

This change improves the recommendation for good commit messages to
include release notes on package bumps.

Including the release notes increases the likelihood that they will be
taken into consideration during review. Having them included in the
review is important to be able to judge whether changes made during a
version bump are sensible, sufficient or complete.

The burden of retrieving the release notes for arbitrary package bumps
should not rest on the relatively small group of reviewers.

Signed-off-by: Martin Weinelt <[email protected]>

CONTRIBUTING.md

@@ -51,7 +51,7 @@ See the nixpkgs manual for more details on [standard meta-attributes](https://ni
 
 In addition to writing properly formatted commit messages, it's important to include relevant information so other developers can later understand *why* a change was made. While this information usually can be found by digging code, mailing list/Discourse archives, pull request discussions or upstream changes, it may require a lot of work.
 
-For package version upgrades and such a one-line commit message is usually sufficient.
+Package version upgrades usually allow for simpler commit messages, including attribute name, old and new version, as well as a reference to the relevant release notes/changelog. Every once in a while a package upgrade requires more extensive changes, and that subsequently warrants a more verbose message.
 
 ## Rebasing between branches (i.e. from master to staging)