doc: Add Contributing guidelines (#257)

First draft of contributing guidelines for Chproxy, detailing how to contribute code, report a bug or improve the documentation.

Author: Blokje5

CONTRIBUTING.md

@@ -0,0 +1,48 @@
+# Contributing to Chproxy
+
+Thank you for considering to contribute to CHProxy. We value your help on the project, whether it is by:
+
+- Reporting a bug
+- Improving documentation
+- Submitting a fix
+- Proposing new features
+
+## Contributing Code
+
+We use [Github Flow](https://docs.github.com/en/get-started/quickstart/github-flow), so all code changes are made via pull requests.
+
+Before making a pull request, make sure to communicate what you aim to achieve with your PR to smoothen the process. Consider [opening an issue](https://github.com/ContentSquare/chproxy/issues) before creating your PR.
+
+To create a PR:
+
+1. Fork the repo and create your branch from `master`.
+2. If you've added code that should be tested, add tests.
+3. If you've changed APIs or added a new feature, update the documentation.
+4. Ensure the test suite passes.
+5. Make sure your code lints.
+
+For first time contributors running the CI pipelines require explicit maintainer approval. Ping one of the maintainers on your PR to ask for a CI run. Thank you for your understanding.
+
+Note that we do not accept "cosmetic PRs" that functionally do not change anything as they have little value for the project. 
+## Reporting bugs
+
+We use GitHub issues to track public bugs. Report a bug by [opening an issue](https://github.com/ContentSquare/chproxy/issues). You can use the Bug Report template to report an issue with Chproxy.
+
+**Great Bug Reports** tend to have:
+
+- A quick summary and/or background
+- Steps to reproduce
+- What you expected would happen
+- What actually happened
+- Notes:
+  - Do you have any metrics available that might be relevant?
+  - Do you suspect a root cause?
+  - Anything else that can contribute to the report.
+
+## Improving the documentation
+
+We greatly value improvements to the documentation! If you feel like certain areas of Chproxy are not well documented, but are unsure how to document them, you can also help by [opening an issue](https://github.com/ContentSquare/chproxy/issues).
+
+## License
+
+By contributing, you agree that your contributions will be licensed under its MIT License.

README.md

@@ -9,3 +9,7 @@ Chproxy is an HTTP proxy and load balancer for the [ClickHouse](https://ClickHou
 It is an open-source community project and not an official ClickHouse project.
 
 Full documentation is available on [the official website](https://www.chproxy.org/).
+
+## Contributing
+
+See our [contributing guide](./CONTRIBUTING.md)