Refactor the documentation to use the main branch

[sgaist]

Hi,

The number of projects under the jupyter organization that have made the move to use main as default branch has become significant however it is not yet reflected in the developer documentation which might be confusing for newcomers.

Would it be a good time to either mention both branches or just main with a note that there's a migration going on ?

[ivanov]

Hi @sgaist - I think it's up to the individual subprojects to determine what branch to use for development. Can you specify where you think the documentation could be updated to reflect this?

[sgaist]

Hi @ivanov,

One example is the start-contributing.rst file from this repository. All the links are using master however all the projects listed in that file have moved to main. The links are still working because GitHub is currently doing the redirection and also notifying the user when they land on the page.

To the best of my knowledge, there's a will to move all the Jupyter related projects to use main as their default branch hence my proposition to update the documentation to reflect that as well as ensure that the links currently in use don't break if/when GitHub stops doing the redirection.