Create Backdrop upgrade page
Created by: seancolsen
We have a page on Installing CiviCRM in backdrop (recently migrated from the wiki), but we don't have a page on upgrading CiviCRM after it's installed within Backdrop. For comparison, we have upgrade pages for CiviCRM in Drupal, in Wordpress, and in Joomla. I think that if we are to claim we support Backdrop, we need to create a page on upgrading CiviCRM within Backdrop.