Link to ruleset README

The information from the password protected README has been moved there.

Removes a TODO #6
Update location of ruleset json
Ensure codelists are added to static files
Link to codelists correctly
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  Link to codelists correctly
  Ensure codelists are added to static files
  Update location of ruleset json
  Link to ruleset README