Add contributing guidelines

Author: ilyakaznacheev

CONTRIBUTING.md

@@ -0,0 +1,43 @@
+# Contributing to Cleanenv
+
+Thank you for your interest in contributing to Cleanenv!
+
+## How to Contribute
+
+Contributions can take many forms, including bug reports, feature requests, documentation improvements, and code changes. We welcome all contributions that align with the goals of the project.
+
+Please keep in mind that this project is designed to be minimalistic, obvious, and as simple as possible. 
+We prioritize clear and easy-to-understand code over complex or "magical" solutions. 
+If you're considering making a code change that might be considered overcomplicated or not in line with the project's goals, 
+we recommend opening an issue to discuss the change before submitting a pull request.
+
+### Reporting Bugs and Requesting Features
+
+If you've found a bug or have an idea for a new feature, please open an issue on our GitHub repository. Be sure to include as much detail as possible, including steps to reproduce the issue, expected behavior, and actual behavior.
+
+### Contributing Code Changes
+
+If you would like to contribute code changes to the project, please follow these steps:
+
+1. Fork the repository to your own GitHub account.
+2. Create a new branch for your changes.
+3. Make your changes and test them thoroughly.
+4. Submit a pull request (PR) with your changes.
+5. Wait for a project maintainer to review your PR. The review process may take some time, so please be patient.
+6. Respond to any feedback and make any necessary changes to your code.
+7. Once your PR has been approved, it will be merged into the main branch of the repository.
+
+### Code Style and Standards
+
+Try to stick to the existing code style of the project.
+
+### Testing
+
+We rely on unit tests to ensure the quality of our code. 
+Before submitting a PR, please make sure your changes include appropriate tests.
+The number indicating the test code coverage should not decrease.
+
+## Getting Help
+
+If you need help with the project, please don't hesitate to ask. 
+You can get in touch with the project maintainers by opening an issue on the GitHub repository.

README.md

@@ -305,7 +305,9 @@ If you use an older version of Golang in your project, please use an older libra
 
 The tool is open-sourced under the [MIT](LICENSE) license.
 
-If you will find some error, want to add something or ask a question - feel free to create an issue and/or make a pull request.
+If you find some error, want to add something or ask a question - feel free to create an issue and/or make a pull request.
+
+Guidelines for contribution may be found in [CONTRIBUTING.md](CONTRIBUTING.md).
 
 Any contribution is welcome.