Update CONTRIBUTING.md

Author: kgodey

CONTRIBUTING.md

@@ -14,9 +14,10 @@ Conduct][code_of_conduct].
 
 ## Project Documentation
 
-Please consult the `README` if there is one, it should contain or link to
-project documentation. If there is no `README`, please file a GitHub issue to
-create one.
+The `README` in the root of the repository should contain or link to
+project documentation. If you cannot find the documentation you're
+looking for, please file a GitHub issue with details of what
+you'd like to see documented.
 
 When making changes to anything in `src/styles/sass/`, you need to run `npm run css-build` to build the changes made.