Updates for some more info and links.
Tweaks from review

Added beta to title.

Adjusted bolds.

Wording tweaks.
added missing word.
Merge remote-tracking branch 'cholmes/new-invite-text' into cholmes-new-invite-text

* cholmes/new-invite-text:
  added missing word.
  Tweaks from review
  Updates for some more info and links.
more improvements to invite email