docs: specify a commit message format to use

CONTRIBUTING.md

@@ -0,0 +1,29 @@
+# Contributing
+
+## Commit Message Format
+
+The commit message format is as follows:
+
+```
+tag(!): short description
+
+Longer description here if necessary
+```
+
+The `tag` should be one of the following:
+
+- `fix` - for a bug fix
+- `update` - for a backwards compatible enhancement
+- `feature` - for a new feature
+- `perf` - for a code change that improves performance
+- `refactor` - for a code change that isn't one of `fix`, `update`, `feature` or `perf`
+- `build` - for changes that affect the build system or external dependencies
+- `test` - for adding or correcting tests
+- `style` - for changes to the linter or formatter configuration and its results
+- `docs` - for changes to documentation only
+- `other` - for anything that isn't covered by the tags above
+
+If a change is a breaking change then that should be indicated by adding a `!` after the tag.
+
+These tags are an adapted version of the tags [eslint](https://eslint.org/docs/developer-guide/contributing/pull-requests#step-2-make-your-changes) and of the tags [Angular](https://github.com/angular/angular/blob/master/CONTRIBUTING.md#type) use. \
+This commit message format is also inspired by [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/).