chore: adds license and contributing file

CONTRIBUTING.md

@@ -0,0 +1,43 @@
+CONTRIBUTING
+============
+Do you want to contribute to `cheat`? There are a few ways to help:
+
+#### Submit a cheatsheet ####
+Do you have a witty bash one-liner to share? [Open a pull-request][pr] against
+the [cheatsheets][] repository. (The `cheat` executable source code lives in
+[cheat/cheat][cheat]. Cheatsheet content lives in
+[cheat/cheatsheets][cheatsheets].)
+
+#### Report a bug ####
+Did you find a bug? Report it in the [issue tracker][issues]. (But before you
+do, please look through the open issues to make sure that it hasn't already
+ been reported.)
+
+#### Add a feature ####
+Do you have a feature that you'd like to contribute? Propose it in the [issue
+tracker][issues] to discuss with the maintainer whether it would be considered
+for merging.
+
+`cheat` is mostly mature and feature-complete, but may still have some room for
+new features.
+
+#### Add documentation ####
+Did you encounter features, bugs, edge-cases, use-cases, or environment
+considerations that were undocumented or under-documented? Add them to the
+[wiki][]. (You may also open a pull-request against the `README`, if
+appropriate.)
+
+Do you enjoy technical writing or proofreading? Help keep the documentation
+error-free and well-organized.
+
+#### Spread the word ####
+Are you unable to do the above, but still want to contribute? You can help
+`cheat` simply by telling others about it. Share it with friends and coworkers
+that might benefit from using it.
+
+
+[cheat]: https://github.com/cheat/cheat
+[cheatsheets]: https://github.com/cheat/cheatsheets
+[issues]: https://github.com/cheat/cheat/issues 
+[pr]: https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/creating-a-pull-request-from-a-fork
+[wiki]: https://github.com/cheat/cheat/wiki