Create CONTRIBUTING.md

Author: ngfelixl

CONTRIBUTING.md

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+## Contribution guidelines
+
+Contributions are very welcome. Please stick to the [code of conduct](./CODE_OF_CONDUCT.md) and, if possible, follow the issue templates.
+
+
+### Commit message guidelines
+
+Please use the following template for your commit messages.
+
+```
+type(scope): message
+
+message-body
+
+BREAKING CHANGE
+Closes #4746
+```
+
+The message body can be multiple lines without any empty lines in between. If there is a breaking change please add the `BREAKING CHANGE` note.
+If there is a related issue to this commit, please add a line containing `Closes/Fixes/Related to #ISSUENUMBER`. The type may be
+one of the following
+
+- feature (if new features are introduced)
+- fix (if a bug was fixed and no features are introduced)
+- package (for changes related to npm/travis configuration)
+- misc (anything that does not fit in the above)