Contributing guide added

This is a mix between
  * https://gist.github.com/PurpleBooth/b24679402957c63ec426
  *
https://github.com/thoughtbot/factory_bot_rails/blob/master/CONTRIBUTING.md
  * https://gist.github.com/briandk/3d2e8b3ec8daf5a27a62
  * https://github.com/nayafia/contributing-template

CONTRIBUTING

@@ -0,0 +1,34 @@
+# Contributing
+
+
+♥ We love pull requests from everyone !
+
+
+When contributing to this repository, please first discuss the change you wish
+to make via issue, email, or any other method with the owners of this repository
+before making a change. 
+
+## So all code changes happen through Pull Requests
+Pull requests are the best way to propose changes to the codebase. We actively
+welcome your pull requests:
+
+1. Fork the repo and create your branch from `master`.
+2. If you've added code that should be tested, add tests.
+3. If you've added code that need documentation, update the documentation.
+4. Be sure to test your modifications.
+5. Write a [good commit message](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html).
+6. Issue that pull request!
+
+## Code of conduct
+Please note by participating in this project, you agree to abide by the [code of conduct].
+
+[code of conduct]: https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING
+
+## Any contributions you make will be under the MIT Software License
+In short, when you submit code changes, your submissions are understood to be
+under the same [MIT License](http://choosealicense.com/licenses/mit/) that
+covers the project. Feel free to contact the maintainers if that's a concern.
+
+## Report bugs using Github's [issues](https://github.com/jesseduffield/lazygit/issues)
+We use GitHub issues to track public bugs. Report a bug by [opening a new
+issue](https://github.com/jesseduffield/lazygit/issues/new); it's that easy!