Update Loop Information and Links

[marionbarker]

Details:

• mkdocs.yml

  • modify the deprecated pages to nav

• close_loop.md

  • update information and links about Loop

There were some inadvertent whitespace changes; my editor is atom on a mac.

Changes not made:

index.md and new_user.md use \ instead of / in a few places. This causes mkdocs to throw several WARNING lines that claim the links are missing. The links are resolved in the deployed pages.