dev: rename default git branch

[flavorjones]

Public announcement that we'll be renaming the default branch from master to main.

General Rationale for Inclusive Language

Here are some resources that may help provide a rationale for updating the language we use for technical concepts:

• IETF - Terminology, Power and Offensive Language
• Guide: Inclusive Language and Vocabulary for Startups and Tech

Specific Rationale for renaming the Git default branch

Here are links to previous external work on this issue in the OSS and business communities:

• github/renaming: Guidance for changing the default branch name for GitHub repositories
• LKML: Dan Williams: [PATCH] CodingStyle: Inclusive Terminology
• Regarding Git and Branch Naming - Software Freedom Conservancy

[flavorjones]

I've made this change. Please update your local dev environment by running:

git branch -m master main
git fetch origin
git branch -u origin/main main
git remote set-head origin -a