Change OpenGraph description on sign-up page to reflect invite (#11744)

app/views/auth/registrations/new.html.haml

@@ -2,7 +2,7 @@
   = t('auth.register')
 
 - content_for :header_tags do
-  = render partial: 'shared/og'
+  = render partial: 'shared/og', locals: { description: description_for_sign_up }
 
 = simple_form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f|
   = render 'shared/error_messages', object: resource