suggestions to improve 04_github_desktop

[hwick]

https://github.com/hbctraining/reproducibility-tools/blob/master/lessons/04_GitHub_desktop.md

1. move publish repository to immediately after creating repo
   -this would allow us to demonstrate that changes made locally, even when committed, need to be pushed to server
2. add push to the end of the lesson
   -this would explicitly let us show pushing (we explicitly cover pulling)
3. ALTERNATIVELY: have push be at the beginning of next lesson
   -04 is already so long, and 05 is quite short.