Docs: add CONTRIBUTING.md (#85)

Author: not-an-aardvark

CONTRIBUTING.md

@@ -0,0 +1,19 @@
+# Contributing
+
+Please be sure to read the contribution guidelines before making or requesting a change.
+
+## Code of Conduct
+
+This project adheres to the [JS Foundation Code of Conduct](https://js.foundation/community/code-of-conduct). We kindly request that you read over our code of conduct before contributing.
+
+## Filing Issues
+
+* To report a security vulnerability in `eslint-github-bot`, please use our [HackerOne program](https://hackerone.com/eslint).
+* To report an issue that does not have security impact, please [create an issue on GitHub](https://github.com/eslint/eslint-github-bot/issues/new).
+* To create a feature request, [create an issue on GitHub](https://github.com/eslint/eslint-github-bot/issues/new).
+
+    Please keep in mind that `eslint-github-bot` is primarily intended for the ESLint team's use cases. You're welcome to use the code for your own purposes, but we are unlikely to accept a feature request unless we would use the feature for the ESLint team's repositories.
+
+## Contributing Code
+
+Please sign our [Contributor License Agreement](https://cla.js.foundation/eslint/eslint) and read over the [Pull Request Guidelines](https://eslint.org/docs/developer-guide/contributing/pull-requests).