Adjust invitation email for existing users

This rewords the invitation email to remove the reference to needing
to log in and accept (or reject) the invitation.

Additionally, because we already had HTML tags in place, this replaces
using <br><br> with paragraph tags.

resources/views/workspaces/emails/invitation-to-existing-user.blade.php

@@ -1,13 +1,7 @@
-{{__('Hi!')}}
+<p>{{__('Hi!')}}</p>
 
-<br><br>
+<p>{{__(':userName has added you to their workspace on SendPortal!', ['userName' => $invitation->workspace->owner->name])}}</p>
 
-{{__(':userName has invited you to join their workspace on SendPortal!', ['userName' => $invitation->workspace->owner->name])}}
+<p>{{__('Since you already have an account, you have automatically been added to the workspace, and do not need to take any further action.')}}</p>
 
-<br><br>
-
-{{__('Since you already have an account, you may accept the invitation from your account settings screen.')}}
-
-<br><br>
-
-{{__('See you soon!')}}
+<p>{{__('See you soon!')}}</p>