CONTRIBUTING.md (#258)

* first draft of CONTRIBUTING.md

* feedback'd:

- added link to @kentcdodd's contributing how-to course
- moved checklist to the top

CONTRIBUTING.md

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+# Contributing
+
+Thanks for your interest in helping out! Here are a **few** _weird_ tricks to
+~~cut your mortgage in half~~ maximize the global net efficiency of your efforts!
+
+## TL;DR: Checklist
+
+When opening an [issue](#issues):
+- [ ] search open/closed issues
+- [ ] discuss bug/enhancement in new or old issue
+
+[PR](#prs) time:
+- [ ] write tests
+- [ ] implement feature/fix bug
+- [ ] update docs
+- [ ] make a note in change log
+
+Remember, you don't need to do it all yourself; any of these are helpful! 😎
+
+## Issues
+
+### Search open + closed issues for similar cases.
+
+  You may find an open issue that closely matches what you are thinking. You
+  may also find a closed issue with discussion that either solves your problem
+  or explains why we are unlikely to solve it in the near future.
+
+  If you find a matching issue that is open, and marked `accepted` and/or `help
+  wanted`, you might want to [open a PR](#prs).
+
+### Open an issue.
+
+  Let's discuss your issue. Could be as simple as unclear documentation or a
+  wonky config file.
+  If you're suggesting a feature, it might exist and need better
+  documentation, or it might be in process. Even given those, some discussion might
+  be warranted to ensure the enhancement is clear.
+
+  You're welcome to jump right to a PR, but without a discussion, can't make any
+  guarantees about merging.
+
+  That said: sometimes seeing the code makes the discussion clearer.😄
+
+This is a helpful contribution all by itself. Thanks!
+
+## PRs
+
+If you would like to implement something, firstly: thanks! Community contributions
+are a magical thing. Like Redux or [the flux capacitor](https://youtu.be/SR5BfQ4rEqQ?t=2m25s),
+they make open source possible.
+
+**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).
+
+Here are some things to keep in mind when working on a PR:
+
+#### Tests
+
+A PR that is just failing test cases for an existing issue is very helpful, as this
+can take as much time (if not more) as it takes to implement a new feature or fix
+a bug.
+
+If you only have enough time to write tests, fantastic! Submit away. This is a great
+jumping-off point for a core contributor or even another PR to continue what you've started.
+
+#### Docs
+
+For enhancements to rules, please update the docs in `docs/rules` matching the rule
+filename from `src/rules`.
+
+Also, take a quick look at the rule summary in [README.md] in case it could use tweaking,
+or add a line if you've implemented a new rule.
+
+Bugfixes may not warrant docs changes, though it's worth skimming the existing
+docs to see if there are any relevant caveats that need to be removed.
+
+#### Changelog
+
+Please add a quick blurb to the [**Unreleased**](./CHANGELOG.md#unreleased) section of the change log. Give yourself
+some credit, and please link back to the PR for future reference. This is especially
+helpful for resolver changes, as the resolvers are less frequently modified and published.
+
+Note also that the change log can't magically link back to Github entities (i.e. PRs,
+issues, users) or rules; there are a handful of footnote URL definitions at the bottom.
+You may need to add one or more URL if you've square-bracketed any such items.
+
+## Code of Conduct
+
+This is not so much a set of guidelines as a reference for what I hope may become
+a shared perspective on the project. I hope to write a longer essay to this end
+in the future. Comments are welcome, I'd like this to be as clear as possible.
+
+### Empathy
+
+People have feelings and perspectives, and people say and believe things for good reasons.
+
+If you find that you summarily disagree with a perspective stated by someone else,
+you likely each have histories that have moved you in opposite directions on a continuum
+that probably does not have a "wrong" or "right" end. It may be that you simply
+are working toward different goals that require different strategies. Every decision
+has pros and cons, and could result in some winners and some losers. It's great to
+discuss this so that both are well-known, and realize that even with infinite discussion,
+cons and losers will likely never go to zero.
+
+Also note that we're not doing brain surgery here, so while it's fine if we spend some time
+understanding each other, cordial disagreement should not be expensive in the
+long run, and we can accept that we will get some things wrong before we get them right (if ever!).
+
+If we can all get together behind the common goal of embracing empathy, everything else should be able to work itself out.
+
+#### Attribution
+
+Thanks for help from http://mozillascience.github.io/working-open-workshop/contributing/
+for inspiration before I wrote this. --ben
+
+[README.md]: ./README.md