Add help text to signup form

- first pass on verbage
- 🙏 thanks to crispy forms this is stupid easy

Closes #68
5 jobs for 68-signup-help in 2 minutes and 52 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed Go-py2.7 #2729

00:01:32

passed Go-py3.4 #2730

00:01:39

passed Go-py3.5 #2731

00:01:35

passed Go-py3.6 #2732

00:01:36

 
  Lint
passed Go-flake8 #2733

00:01:13