feat(CONTRIBUTING): new file for GitHub friendliness

CONTRIBUTING.md

@@ -0,0 +1,25 @@
+# Contributing
+
+Thanks for your interest. Contributions are welcome!
+
+> Please note that this project is released with a [Contributor Code of Conduct](CODE_OF_CONDUCT.md). By participating in this project you agree to abide by its terms.
+
+Check the [Issues](https://github.com/olets/zsh-abbr/issues) to see if your topic has been discussed before or if it is being worked on. You may also want to check the roadmap (see above). Discussing in an Issue before opening a Pull Request means future contributors only have to search in one place.
+
+This project loosely follows the [Angular commit message conventions](https://docs.google.com/document/d/1QrDFcIiPjSLDn3EL15IJygNPiHORgU1_OOAqWjiDU5Y/edit). This helps with searchability and with the changelog, which is generated automatically and touched up by hand only if necessary. Use the commit message format `<type>(<scope>): <subject>`, where `<type>` is **feat** for new or changed behavior, **fix** for fixes, **docs** for documentation, **style** for under the hood changes related to for example zshisms, **refactor** for other refactors, **test** for tests, or **chore** chore for general maintenance (this will be used primarily by maintainers not contributors, for example for version bumps). `<scope>` is more loosely defined. Look at the [commit history](https://github.com/olets/zsh-abbr/commits/master) for ideas.
+
+Tests are in the `tests` directory. To run them, replace `zsh-abbr` with `zsh-abbr/tests` in .zshrc. For example, zinit users will run
+
+```shell
+zinit ice lucid
+zinit light olets/zsh-abbr/tests
+```
+
+in place of
+
+```shell
+zinit ice lucid
+zinit light olets/zsh-abbr
+```
+
+Open a new session and the tests will run.

ROADMAP.md

@@ -18,7 +18,7 @@ Key:
 
 Github
 
-- [ ] move contribution documentation to a CONTRIBUTING.md
+- [x] move contribution documentation to a CONTRIBUTING.md
 
 Chrome