add contributing guide (#61)

CONTRIBUTING.md

@@ -0,0 +1,24 @@
+Any contributions are welcome.
+
+## Setup
+
+This project uses [pnpm](https://pnpm.io/installation). Please install it if you haven't.
+
+Then install dependencies to finish the setup.
+
+```
+pnpm install
+```
+
+## Development
+
+- `pnpm test` to run tests.
+- `pnpm lint` to run linting and type-checking.
+- `pnpm build` to build.
+
+## Maintainers
+
+Feel free to mention them if you have questions.
+
+- [@yukukotani](https://github.com/yukukotani)
+- (Inactive) [@no-yan](https://github.com/no-yan)

README.md

@@ -54,6 +54,10 @@ Every rule is fixable with `eslint --fix`.
 - [`props-shorthand`](https://github.com/yukukotani/eslint-plugin-chakra-ui/blob/main/docs/rules/props-shorthand.md): Enforces the usage of shorthand property or vice-versa
 - [`require-specific-component`](https://github.com/yukukotani/eslint-plugin-chakra-ui/blob/main/docs/rules/require-specific-component.md): Enforces the usage of specific Chakra components instead of Box components with an attribute.
 
+## Contributing
+
+See [contributing guide](CONTRIBUTING.md).
+
 ## Prior Art
 
 This plugin is inspired by [eslint-plugin-tailwind-css](https://github.com/francoismassart/eslint-plugin-tailwindcss).