demonstrate screen() in README

Fixes #457
3 jobs for mk-screen-in-readme in 8 minutes and 58 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test Basic
passed docker:v1.6 #303338

00:07:43

passed format #303337
privileged

00:01:54

 
  Documentation
passed doc-tests:v1.6 #303339

00:01:15