docs(README): update contributing guidelines

* Apply the Contributor Covenant Code of Conduct to projects by default.
* Reference How to Contribute to Open Source in the Open Source Guides
  for new contributors.

Signed-off-by: Kevin Locke <[email protected]>

Author: kevinoid

README.md

@@ -50,8 +50,13 @@ Documentation](https://kevinoid.github.io/project-template/api).
 
 ## Contributing
 
-Contributions are welcome and very much appreciated!  Please add tests to
-cover any changes and ensure `npm test` passes.
+Contributions are appreciated.  Contributors agree to abide by the [Contributor
+Covenant Code of
+Conduct](https://www.contributor-covenant.org/version/1/4/code-of-conduct.html).
+If this is your first time contributing to a Free and Open Source Software
+project, consider reading [How to Contribute to Open
+Source](https://opensource.guide/how-to-contribute/)
+in the Open Source Guides.
 
 If the desired change is large, complex, backwards-incompatible, can have
 significantly differing implementations, or may not be in scope for this