(Docs) Note in installation pages that PuppetDB is installed as part of PE 3.0+
Merge pull request #732 from nfagerlund/puppetdb_is_in_pe

(Docs) Note in installation pages that PuppetDB is installed as part of ...
Merge branch '1.5.x'

* 1.5.x:
  (Docs) Note in installation pages that PuppetDB is installed as part of PE 3.0+