Change the "invalid username or password" hint on login after N erroneous tries #1146
Description
Some self hosted users can't login to their site because they don't know they have to enter their website url.
We should keep the current hint "invalid username or password", and add " - If you're a self hosted WordPress.org user, don't forget to tap Add Self Hosted Site and fill the URL field" after 2 "invalid username or password" errors.