DOC: update guidelines to create module branches

[Lucia-Fonseca]

Description

The contributing guidelines should be updated to reflect how to create a new module branch.
Example:

git checkout -b module/module_name main

And when first pushed

git push --set-upstream origin module/module_name

[rrjbca]

IMO creating and maintaining module branches is a matter for coordinators and/or repo maintainers and so so should not be in contributor guidelines. In fact the branch protection rules will not allow non-admins to create branches in the way you suggest. Perhaps a new doc "maintainer guidelines" is needed outlining tasks specifically for maintainers such as this, creating releases etc.

What I do think needs to be in the contributor docs is a sentence to the effect of "If you are making a contribution to a new module that has not yet been merged into the main branch, you should set the target branch of your pull request to the appropriate module branch instead of main"

[rrjbca]

Perhaps also guidelines on what to do if you want to propose a new module (in discussion pages?)

[Lucia-Fonseca]

Agreed.