(DOC-1190) Revise directory environments docs for new behavior around main manifest

- The default main manifest is now configurable instead of being hardcoded
- It's now possible to lock all environments to a global manifest
Merge pull request #381 from laurenrother/puppet37

Add Modulefile information to Deprecations page.
Modify wording of modulefile deprecation, add detect-and-update steps
Update file paths and Win install page with best known info about filesystem redirection
Remove '2003 only' note
quick edits to format