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. Testing Done: Built docs and checked the results.