Add contributing guidelines (#146)

This pull request adds a CONTRIBUTING.md file that provides setup
instructions, testing and linting commands, and guidelines for creating
a pull request.

---------

Signed-off-by: hsm207 <[email protected]>

CONTRIBUTING.md

@@ -0,0 +1,62 @@
+# Community contributions
+
+We welcome community contributions.
+
+In order to facilitate an easier contribution and review process, we provide the following guidelines. Please review them before creating a pull request.
+
+This will improve the chances of your contribution being accepted, by facilitating a higher code quality, and help the maintainers to review the code as well.
+
+### Setup
+
+We recommend that you use [development containers](https://containers.dev/) to contribute to this integration.
+
+Please refer to the files in the `.devcontainer` folder for the specification of the development container for this repository.
+
+If you are new to dev containers, check out a tutorial for your IDE, such as [this one for VS Code](https://code.visualstudio.com/docs/devcontainers/containers).
+
+#### Installation
+
+To install all dependencies, run the following command:
+
+```shell
+poetry install --with test,dev,lint,test_integration
+```
+
+Note: This command is run automatically when you start the development container.
+
+### Testing
+
+To run the tests, use the following command:
+
+```shell
+make test
+```
+
+### Linting
+
+To run the linter, use the following command:
+
+```shell
+make format
+```
+
+### Creating a Pull Request
+
+For minor changes, such as fixing typos in documentation or updating workflows and dependencies, feel free to directly submit a pull request (PR). For more substantial contributions like bug fixes or new features, we encourage you to first have a discussion with the project maintainers. This helps us align on the design of the solution and ensures your efforts are on the right track. You can do this by raising a new issue or volunteering to work on an existing one. Please wait to be assigned an issue before starting your work.
+
+1. Fork the repository.
+2. Create a new branch from the `main` branch.
+3. Make your changes.
+4. Run the tests and linter. Make sure the tests pass.
+5. Commit your changes.
+6. Push your branch to your fork.
+7. Create a PR.
+8. In the PR, describe your changes and tag the issue e.g. (#123) that it fixes.
+9. Label your PR with one of the following labels:
+    - `bug`: If the PR fixes a bug.
+    - `documentation`: If the PR only changes the documentation.
+    - `enhancement`: If the PR adds new functionality.
+    - `quality-improvement`: If the PR is about enhancements to code or workflows for better quality, robustness, performance, etc.
+
+   Additionally, if the PR is a breaking change, add the `breaking` label.
+10. Address review comments, if any.