Add urgency to the email confirmation message

[emcoding]

This is the email body we are sending:

  You've recently logged into the RGSoC teams app with your GitHub account and
  created a profile. In order to get the best out of the Teams app (like creating
  a team or submitting a project), we'll need to confirm your email address. To
  confirm your email, click <a href="http://localhost:3000/users/[et-cetera]">here</a>

1. 'created a profile' is not per se what happened; what happened is either their first sign in, or they changed their email address.
2. The need to confirm is not 'to get the best out of it' imo. It is more like 'to complete your registration'.