docs: add contribution section to readme

New guidelines for contribution. Added information to support the usage of Conventional Commits.

README.md

@@ -44,13 +44,30 @@ Everything has its default style.
 
 CSS classes follow a naming scheme of `<object>_<description>`.
 
-* *Object* usually is the name of the HTML element. If it is not a elemtn directly it is the thing which receives the styling
-* *Description* is a name of the style e.g. what it does, how it looks
+- *Object* usually is the name of the HTML element. If it is not a elemtn directly it is the thing which receives the styling
+- *Description* is a name of the style e.g. what it does, how it looks
 
 ## Versioning
 
 This project uses [SemVer](http://semver.org/) for versioning. For the versions available, see the [tags on this repository](https://quelltext.interaktionsweise.de/interaktionsweise/hippie/tags).
 
+## Contribution
+
+For contribution please use the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/#summary) specification.  
+The commit *type* can include the following:
+
+- feat – A new feature is introduced with the changes
+- fix – A bug fix has occurred
+- chore – Changes that do not relate to a fix or feature and don't modify src or test files (for example updating dependencies)
+- refactor – Refactored code that neither fixes a bug nor adds a feature
+- docs – Updates to documentation such as a the README or other markdown files
+- style – Changes that do not affect the meaning of the code, likely related to code formatting such as white-space, missing semi-colons, and so on.
+- test – Including new or correcting previous tests
+- perf – Performance improvements
+- ci – Continuous integration related
+- build – Changes that affect the build system or external dependencies
+- revert – Reverts a previous commit
+
 ## Authors
 
 **Stephan Hagedorn** - *Initial work* - [Interaktionsweise](https://interaktionsweise.de)