master branch has been renamed to main

[John Wiegley]

Hi everyone,

Just a heads up that the default branch for the C++Ledger branch has been switched on GitHub from `master` to `main`. In order to update your local clones you can execute the following commands:

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

I did this because most of the rest of the projects I work on now use `main`, so I kept finding myself mixing up the two more times than I care to admit.

My apologies for any disruptions,

  John

[Alexis]

Hi John,

thanks for including the git commands,
they made it easy to adapt to the branch renaming in local clones.


Best
Alexis