Set Up a Separate Repository for Learners

[sdhutchins]

Per the Carpentries:

"If you are teaching Git, you should create a separate repository for learners to use in that lesson.
You should not have them use the workshop website repository because:

• your workshop website repository contains many files that most learners don't need to see during
  the lesson, and

• you probably don't want to accidentally merge a damaging pull request from a novice Git user into
  your workshop's website while you are using it to teach.

You can call this repository whatever you like, and add whatever content you need to it."