Add CONTRIBUTING.md

Fixes #141

CONTRIBUTING.md

@@ -0,0 +1,35 @@
+# Contributing to `auto-changelog`
+
+Installing the library locally is relatively easy:
+
+```bash
+git clone https://github.com/CookPete/auto-changelog.git
+cd auto-changelog
+yarn # or npm install
+```
+
+You can then run it with simply:
+
+```bash
+node src/index.js
+```
+
+## Linting
+
+This project uses [standard](https://github.com/feross/standard) code style. Be sure to lint the code after making changes and fix any issues that come up.
+
+```bash
+yarn lint # or npm run lint
+```
+
+## Testing
+
+This project uses [mocha](https://github.com/mochajs/mocha) and [chai](https://github.com/chaijs/chai) for testing. Be sure to run tests after making changes and, if you’re feeling generous, add some tests of your own.
+
+```bash
+yarn test # or npm test
+```
+
+## Becoming a sponsor
+
+A great way to show your appreciation and get an issue bumped to a higher priority is to [become a sponsor on Patreon](https://www.patreon.com/cookpete).