[DISCUSS] rename master branch to owb_2.0.x?

[Mark Struberg]

Hi!

I've created a new 'main' branch to contain our work on OWB-4.0.
Should we make this branch the new default branch in gitbox/gibhub and move the 
current master to be owb_2.0.x to indicate the maintenance status?

LieGrue,
strub