Broken link to Drush cron instructions in config form

The default branch for the project is still set to 8.x-1.x so new branches default to that. Because this was a single line change, I was able to create a valid MR from 8.x-1.x -> 2.x, but updating the default branch would help potential contributors avoid that mistake.

Set the default branch in Gitlab

Automatically closed - issue fixed for 2 weeks with no activity.