Allow copying a github link to the default branch

i'd like to be able to copy a GitHub link to the default branch on github.

this extension already provides useful commands to work with github links:

• Copy GitHub Permalink
• Copy GitHub Head Link
• Open Permalink on Github

however I am often wanting to link people to the main branch, and not whatever my HEAD is pointing at which might not even be pushed up to github. so something like "Copy Github Default Branch Link" or similar help me generate the kind of links I am most often looking to share.