Update README template regarding users

[dacur]

The template says:

### Seeded logins

For a list of credentials you can use to log into the app, check [the seeds file](db/seeds.rb).
These logins are created via `rails db:setup` above.

There aren't any credentials being made, unless I'm missing something. This should be updated, removed, or the seeds file should create a User with login credentials. 😄

[dkniffin]

Yep, very true. I think I recently updated the seeds file and accidentally removed that part. We should create a user in db/seeds/user.rb