Change primary branch from "master" to "main"

[egillespie]

GitHub now creates repositories using main as the primary branch. However, the lansingcodes repositories still use the old default branch name master. Lansing Codes is committed to creating a welcoming and inclusive community. To make strides toward that goal, we want to rename all of our master branches to main.

To rename master to main, follow these steps:

1. Use Git Tower's Guide to rename master to main
2. Update references to master in the repository's docs (Contributing Guide, README, etc.) to say main (if applicable)
3. Update CI/CD workflows to look at main instead of master (if applicable)
4. Broadcast to other contributors that the branch has been changed, and share What your teammates need to do

[egillespie]

Default branch renamed to main. GitHub, Netlify, and docs have been updated to reflect the change.