1d7480998c
This is a straight port of the [Google doc](https://docs.google.com/document/d/1NQtokvmDaBnMhaAzLBYEo8Mk9SmVmksrBkwH-XB4rsk/edit#). I took new screenshots @2x, used "address bar" instead of "urlbar" since that's what our docs use, and tweaked some things here and there, but nothing major. It will probably be a pain to keep this updated, but so it goes for docs. Differential Revision: https://phabricator.services.mozilla.com/D115975