Change the material to <repository-name> and <fork-name> so that there is no confusion between what the instructor is saying and the notes

The notes use `git-training-demo` as the test repo but we used repos with dates in as well since we did so many workshops.
We could change the lesson notes to be more generic.

Search the lesson notes for `git-training-demo` and read the surrounding workshop material to identify references that depend on a dated repository name. Replace those examples with generic `` and `` wording, then review the notes to confirm the instructor’s instructions and learner notes are no longer confusing.

Written by the indexing model from the issue text.