Flavors are undocumented

[markvoelker]

When creating an autobuilding package source, the user is asked to select a "Flavor". Options are "OpenStack", "Puppet", and "Native". However there's no explanation in the documentation about what these mean. OpenStack and Puppet seem fairly intuitive, although I suppose there's some room for questions (e.g. is, say, a custom Quantum plugin that's not in the official OpenStack Quantum repository still an "OpenStack" flavor?), but Native not so much....e.g. is this is a catch-all for anything not OpenStack and not Puppet?

We should probably add some documentation explaining what these mean.