Set the default branch to 2.0.x

Problem/Motivation

When creating an Issue Fork using the Create Issue Fork button a new branch is automatically created from the default branch.
Currently the default branch is set to 8.x-1.x, which is problematic.

Remaining tasks

Follow the instructions in this article to set the default branch to 2.0.x https://www.drupal.org/docs/develop/managing-a-drupalorg-theme-module-or... →

User interface changes

API changes

Data model changes