(#13695) add README about puppetlabs_spec_helper
Merge branch 'cprice-puppet-ticket/master/13695-readme-about-puppetlabs-spec-helper'

* cprice-puppet-ticket/master/13695-readme-about-puppetlabs-spec-helper:
  (#13695) add README about puppetlabs_spec_helper

[ci skip]
closes #63