Updated instructions to install Focus for Android Nightly and Beta

Hello localizers,
Quick message to tell you that there are updated instructions so you can test your work on Focus Android Nightly or Beta.
Just follow these instructions:

First, visit https://groups.google.com/g/firefox-focus-pre-release and join the Google Group (use the same Google account you use on your device to download apps from Google Play)

For Beta releases:

  1. After you have joined the group, opt-in to receive Beta builds, (again with the same Google account): https://play.google.com/apps/testing/org.mozilla.focus.beta
  2. Download Firefox Focus (Beta) from Google Play: https://play.google.com/store/apps/details?id=org.mozilla.focus.beta

For Nightly releases:

  1. After you have joined the group opt-in, to receive Nightly builds, (again with the same Google account): https://play.google.com/apps/testing/org.mozilla.focus.nightly
  2. Download Firefox Focus (Nightly) from Google Play: https://play.google.com/store/apps/details?id=org.mozilla.focus.nightly

Note that I am currently updating these instructions in Pontoon and docs. thank you!