NOTICE: master branch renamed to main

[ethanwhite]

I've just renamed the default branch for this repository from master to main in line with broader efforts towards more inclusive naming.

Existing contributors will need to update their local repository settings. If you only work directly with the main repository (i.e., you do not have your own fork) then run the following commands in the terminal when in the root directory for repo:

git branch -m master main
git fetch origin
git branch -u origin/main main

If you have a fork then you need to update the upstream branch instead. Assuming you've call it upstream the commands would be:

git branch -m master main
git fetch upstream
git branch -u upstream/main main

If you've named the main repository something different then use the appropriate name.

Thanks to @trashbirdecology ecology for requesting this in #126 and @ha0ye for initial work to get this going. See https://github.com/github/renaming for more details and to do this for your own repositories if interested.

[ethanwhite]

Closing since the notice has been open for three months.