Create some "get things done faster" marketing content

[jenlampton]

This is a follow-up to #687

From @klonos:

we could add a new feature called "Get things done faster and easier", separate to the "Upgrade from Drupal 7" feature

Get things done faster and easier out-of-the-box

People with previous Drupal experience will find the admin interface in Backdrop familiar, with the addition of usability improvements and new features. We have moved things where content editors and site administrators expect to find them; so working with Backdrop should be more intuitive and require less work.

^^ I have tried to capture various personas there:

site owners: save money
developers: work faster with things they already know -> no need to rewrite big chunks of code -> less work allows them to make competitive pitches
content editors: no need to learn how to use a new interface
site admins: less work -> easier management of the site