doc: add note about folders to CONTRIBUTING.md

CONTRIBUTING.md

@@ -8,6 +8,11 @@ the repository's language and add a new entry like this:
 Save the file and then run `./scripts/add-badges.py` on the command
 line and then commit your changes.
 
+Don't link to files or folder within the tree since that messes up the
+badges.  Users will be able to figure out where the code for the
+current year is if you use the same repo for multiple years so don't
+worry about it.
+
 Adding your own repos is perfectly fine, but don't add the same repo
 to multiple sections.  If you use multiple languages, then you should
 add your repo to the "Polyglot" section.