Rename master branch

[brentzundel]

Summary

We should rename the branch master to main and use that going forward for our work.

From Problematic Terminology in Open-Source on master/slave terminology in software:

Use of this term is problematic. It references slavery to convey meaning about the relationship between two entities.

Removing this terminology from our workflow is a small gesture to include more people from marginalized groups in this project.

(I’m open to names other than main)

Technical Steps

• create main branch from master
• make main the default GitHub branch
• modify github/central to use main for release notes reloading
• redirect PRs to main in hyperledger/indy-plenum
• move branch protections from master to main
• modify docs to reference main instead of master
• delete master branch to avoid confusion?

Feedback?

[WadeBarnes]

Done