This change rearranges the RBTools documentation to try to simplify some

things:


Moved info about .reviewboardrc files to the main "configuration"

  page, and clarified where different files are loaded from and in what

  priority order.


Updated repo configuration page to emphasize why a .reviewboardrc file

  is a good idea and moved the alternative methods up next to that so

  it's clear what they're for.

Moved the ENABLE_PROXY documentation from repository config to user

  config.
Split the docs about aliases out into its own page.
On the main index page, simplified the "Getting Started" section to be

  install, configure, use.
Moved links for authentication and TFS into the "Common RBTools

  workflows" section.

Built docs and checked the results.