Add CONTRIBUTING info

CONTRIBUTING.md

@@ -0,0 +1,23 @@
+# Contributing
+
+To get setup in the environment and run the tests, take the following steps:
+
+```bash
+python3 -m venv env
+source env/bin/activate
+pip install -e '.[testing]'
+
+bootstrap
+
+flake8
+coverage run && coverage report
+```
+
+## Test Coverage
+
+Pull requests that make changes or additions that are not covered by tests
+will likely be closed without review.
+
+In addition, all tests must pass the tests **AND** flake8 linter. If flake8
+exceptions are included, the reasoning for adding the exception must be included
+in the pull request.