Clarify when changelog entries are necessary

CONTRIBUTING.md

@@ -6,10 +6,31 @@ Thank you for considering to contribute to `bat`!
 
 ## Add an entry to the changelog
 
-If your contribution changes the behavior of `bat` (as opposed to a typo-fix
-in the documentation), please update the [`CHANGELOG.md`](CHANGELOG.md) file
-and describe your changes. This makes the release process much easier and
-therefore helps to get your changes into a new `bat` release faster.
+Keeping the [`CHANGELOG.md`](CHANGELOG.md) file up-to-date makes the release
+process much easier and therefore helps to get your changes into a new `bat`
+release faster. However, not every change to the repository requires a
+changelog entry. Below are a few examples of that.
+
+Please update the changelog if your contribution contains changes regarding
+any of the following:
+  - the behavior of `bat`
+  - syntax mappings
+  - syntax definitions
+  - themes
+  - the build system, linting, or CI workflows
+
+A changelog entry is not necessary when:
+  - updating documentation
+  - fixing typos
+
+>[!NOTE]
+> For PRs, a CI workflow verifies that a suitable changelog entry is
+> added. If such an entry is missing, the workflow will fail. If your
+> changes do not need an entry to the changelog (see above), that
+> workflow failure can be disregarded.
+
+
+### Changelog entry format
 
 The top of the `CHANGELOG` contains a *"unreleased"* section with a few
 subsections (Features, Bugfixes, …). Please add your entry to the subsection