Update README to remove 8.0-dev branch information (#1459)
Update README to remove 8.0-dev branch information (#1459)

* Remove 8.0-dev branch info from README

* Update README

* Fix nits

mozilla-mobile/focus-ios,mozilla-mobile/focus,mozilla/focus,mozilla-mobile/focus-ios,justindarc/focus,mozilla-mobile/focus,mozilla/focus,justindarc/focus,mozilla-mobile/focus-ios,justindarc/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus,justindarc/focus,justindarc/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus,justindarc/focus,mozilla/focus,mozilla-mobile/focus,mozilla/focus,mozilla/focus