chore: add contribution guidelines (#38)

Author: StyleShit

CONTRIBUTING.md

@@ -0,0 +1,118 @@
+# Contributing
+
+Thank you for your interest in contributing! Whether it's a bug report, feature request, or a pull request, we appreciate your help in improving this ESLint plugin.
+
+## Table of Contents
+
+- [Code of Conduct](#code-of-conduct)
+- [Getting Started](#getting-started)
+- [Development Workflow](#development-workflow)
+- [Linting, Formatting, and Testing](#linting-formatting-and-testing)
+- [Playground](#playground)
+- [Submitting Issues](#submitting-issues)
+- [Submitting Pull Requests](#submitting-pull-requests)
+- [Resources](#resources)
+
+## Code of Conduct
+
+We adhere to the [OpenJS Foundation Code of Conduct](https://github.com/openjs-foundation/cross-project-council/blob/main/CODE_OF_CONDUCT.md). Please be respectful, inclusive, and constructive in all your communications and contributions.
+
+If you're new to open source, this guide might also be helpful:
+[How to Contribute to Open Source](https://opensource.guide/how-to-contribute/)
+
+## Getting Started
+
+To contribute, **fork the repository**, then clone your fork and install dependencies:
+
+```bash
+git clone https://github.com/YOUR_USERNAME/eslint-plugin-php.git
+cd eslint-plugin-php
+npm install
+```
+
+> Replace `YOUR_USERNAME` with your actual GitHub username.
+
+## Development Workflow
+
+1. **Create a new branch** for each feature or fix:
+
+   ```bash
+   git checkout -b fix/rule-name-or-feature
+   ```
+
+2. **Make changes** to the codebase:
+
+   - Rules live in `src/rules/`
+   - Tests go in `src/rules/__tests__/`
+   - Add it to the `recommended` config (under `src/configs/recommended.ts`)
+
+3. **Document your rule:**
+
+   - Update the rules list in `README.md`
+
+## Linting, Formatting, and Testing
+
+Run the following before committing:
+
+```bash
+npm run lint       # Check for linting issues
+npm run format     # Format code with Prettier
+npm run test           # Run all tests
+```
+
+To run tests for a specific rule:
+
+```bash
+npm run test rule-name
+```
+
+> Replace `rule-name` with the file name of your rule.
+
+## Playground
+
+If you want to test how the rules work on PHP code, you can use the **playground** directory. This allows you to quickly run the plugin on sample PHP files.
+
+1. Place your PHP code in the `/playground` directory.
+2. Run the following command to lint the files using the local project rules:
+
+```bash
+npm run playground
+```
+
+This will lint all the PHP files in the `/playground` directory with the plugin's current rules.
+
+Don't forget to build your code before running the playground, to ensure all changes are included in the linting process:
+
+```bash
+npm run build
+```
+
+You can also use `npm run build -- --watch` to automatically rebuild your code when you make changes.
+
+## Submitting Issues
+
+If you find a bug or want to request a feature, please open an issue and include:
+
+- A clear description of the problem
+- Code snippets or test cases
+- ESLint and `eslint-plugin-php` versions
+
+## Submitting Pull Requests
+
+1. Push your changes to your fork.
+2. Open a pull request to the `main` branch of the original repository.
+3. Include:
+   - Tests for your rule or fix
+   - Updates to the rule list in the README (if applicable)
+   - Entry in the recommended config (if applicable)
+4. Make sure all lint, format, and test checks pass.
+
+We’ll review your PR as soon as possible. Thank you for contributing to `eslint-plugin-php`!
+
+## Resources
+
+- **Creating custom ESLint rules**:  
+  https://eslint.org/docs/latest/extend/custom-rules
+
+- **Explore the PHP AST**:  
+  Use [AST Explorer](https://astexplorer.net/) with the **PHP** language selected to view and understand abstract syntax trees. This is very helpful for rule development.

README.md

@@ -68,6 +68,6 @@ export default defineConfig([
 | `php/no-array-keyword`    | Disallow the use of the array keyword               | 🔧  |     | ✅  |
 | `php/require-visibility`  | Require visibility for class methods and properties |     | 💡  | ✅  |
 
-## Development
+## Contributing
 
-Use `npm run playground` to lint local PHP files under the `playground` directory.
+Contributions are welcome! Please read the [contributing guidelines](CONTRIBUTING.md) for more information.