docs: Add CONTIBUTING.md (#69)

This PR includes:
- [x] - Adding `CONTRIBUTING.md`
- [x] - Setting up `husky` with `commitlint` to force meaningul commit messages

Fixes #62

CONTRIBUTING.md

@@ -0,0 +1,65 @@
+# Contributing to React Native CLI
+
+## Development Process
+
+All work on React Native CLI happens directly on GitHub. Contributors send pull requests which go through review process.
+
+> **Working on your first pull request?** You can learn how from this *free* series: [How to Contribute to an Open Source Project on GitHub](https://egghead.io/series/how-to-contribute-to-an-open-source-project-on-github).
+
+1. Fork the repo and create your branch from `master` (a guide on [how to fork a repository](https://help.github.com/articles/fork-a-repo/)).
+2. Run `yarn` or `npm install` to install all required dependencies.
+3. Now you are ready to do the changes.
+
+## Repository
+
+Repository is splitted into two packages:
+
+* `local-cli` - Historically, it was included in `react-native` package. Contains all the commands code.
+* `global-cli` - Historically, it was a `react-native-cli` package and the only reason this package existed was to initialize an empty project.
+
+## Testing your changes
+
+You can test your changes by calling `cli.js` directly from the cloned repository. You need to make sure the version of React Native matches the one present in devDependencies of the CLI. Otherwise, you may get unexpected errors.
+
+```sh
+node /path/to/cloned/project/packages/local-cli/cli.js
+```
+
+## Typechecking, linting and testing
+
+Currently we use `flow` for typechecking, `eslint` with `prettier` for linting and formatting the code and `jest` for testing.
+
+* `yarn flow`: run `flow`
+* `yarn lint`: run `eslint` and `prettier`
+* `yarn test`: run unit tests
+
+## Commit message convention
+
+We prefix our commit messages with one of the following to signify the kind of change:
+
+* **build**: Changes that affect the build system or external dependencies
+* **ci**, **chore**: Changes to our CI configuration files and scripts
+* **docs**: Documentation only changes
+* **feat**: A new feature
+* **fix**: A bug fix
+* **perf**: A code change that improves performance
+* **refactor**: A code change that neither fixes a bug nor adds a feature
+* **style**: Changes that do not affect the meaning of the code
+* **test**: Adding missing tests or correcting existing tests
+
+## Sending a pull request
+
+When you're sending a pull request:
+
+* Prefer small pull requests focused on one change.
+* Verify that `flow`, `eslint` and all tests are passing.
+* Preview the documentation to make sure it looks good.
+* Follow the pull request template when opening a pull request.
+
+## Reporting issues
+
+You can report issues on our [bug tracker](https://github.com/react-native-community/react-native-cli/issues). Please follow the issue template when opening an issue.
+
+## License
+
+By contributing to React Native CLI, you agree that your contributions will be licensed under its **MIT** license.

commitlint.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  extends: ['@commitlint/config-conventional'],
+};

package.json

@@ -10,13 +10,21 @@
   },
   "devDependencies": {
     "@callstack/eslint-config": "^3.0.2",
-    "eslint": "^5.10.0"
+    "@commitlint/cli": "^7.2.1",
+    "@commitlint/config-conventional": "^7.1.2",
+    "eslint": "^5.10.0",
+    "husky": "^1.3.1"
   },
   "eslintConfig": {
     "extends": "@callstack",
     "rules": {
       "global-require": 0,
       "no-console": 0
     }
+  },
+  "husky": {
+    "hooks": {
+      "commit-msg": "commitlint -E HUSKY_GIT_PARAMS"
+    }
   }
 }