Add CONTRIBUTING.md file (#585)

Signed-off-by: Miroslav Kovar <miroslav.kovar@absa.africa>

CONTRIBUTING.md

@@ -0,0 +1,13 @@
+## How to contribute
+
+You are encouraged to contribute to the repository by **forking and submitting a pull request**.
+
+For significant changes, please open an issue first to discuss the proposed changes to avoid re-work.
+
+(If you are new to GitHub, you might start with a [basic tutorial](https://help.github.com/articles/set-up-git) and check out a more detailed guide to [pull requests](https://help.github.com/articles/using-pull-requests/).)
+
+Pull requests will be evaluated by the repository guardians on a schedule and if deemed beneficial will be committed to the `main` branch. Pull requests should have a descriptive name and include an summary of all changes made in the pull request description, and include unit tests that provide good coverage of the feature or fix. A Continuous Integration (CI) pipeline is executed on all PRs before review and contributors are expected to address all CI issues identified.
+
+If you would like to propose a significant change, please open an issue first to discuss the work with the community.
+
+Contributions are made pursuant to the Developer's Certificate of Origin, available at [https://developercertificate.org](https://developercertificate.org), and licensed under the Apache License, version 2.0 (Apache-2.0).