(doc) facter.json schema

Added facter.json schema change notes to indicate
that when new facts are added, they should also be
included in the file to pass acceptance tests.
(FACT-699) include new facts in facter.json

This adds the schema of new `rubyplatform` and
`system32` facts to facter.json.
Merge branch 'stable'

* stable:
  (FACT-699) include new facts in facter.json
  (doc) facter.json schema