docs: add contribution guidelines

Author: azat-io

contributing.md

@@ -0,0 +1,41 @@
+# Contributing
+
+Hello! It's great that you are interested in contributing to ESLint Plugin De Morgan. Before submitting your contribution, please take a moment to read the following guide:
+
+## Installation
+
+This project uses the [pnpm](https://pnpm.io) package manager. Therefore, to work with the project, you need to install it.
+
+How to set up a project locally and run tests:
+
+1. Clone repo:
+
+```sh
+git clone [email protected]:azat-io/eslint-plugin-de-morgan.git
+```
+
+2. Install dependencies:
+
+```sh
+pnpm install
+```
+
+3. Run tests:
+
+```sh
+pnpm test
+```
+
+## Pull Request Guidelines
+
+Before create pull request fork this repo and create a new branch.
+
+ESLint Plugin De Morgan aims to be lightweight, so think before adding new dependencies to your project.
+
+Commit messages must follow the [commit message convention](https://conventionalcommits.org/) so that changelogs can be automatically generated.
+
+Make sure tests pass.
+
+## Additional information
+
+This plugin uses [@typescript-eslint/parser](https://github.com/typescript-eslint/typescript-eslint/tree/main/packages/parser). When developing, I recommend using [AST explorer](https://ast-explorer.dev). It makes development much easier.