Add section on changing master to main

[PLNReynolds]

Need to add language and code for renaming branch master to main. Some suggested wording:

When you run git init you will see that 'master' is the default name for the starting (origin) branch. Regardless of benign intent by the software developers, the term 'master' is problematic and serves as a constant reminder of racial injustice. The tech community at large does not want to perpetuate this and has started avoiding that terminology and the only reason you may see it today is because of this artifact. We will therefore change the branch name to the commonly adopted term, 'main' in the terminal by navigating to our repository and typing:

git branch -m master main

NOTE: If you want to work with GitHub, you have to rename all 'master' to 'main' to be able to push and pull your changes as GitHub uses 'main' as default.

If you want to make a global change so all new repositories use main by default:

Add code here, see some examples at this Stack Overflow post.

[t-shoemaker]

@PLNReynolds We already ask participants to make this change in a configuration step, which may be too tucked away/could be highlighted more during the session itself. See this section