Add options to group_vars to make it match docs

In the README, we state that options will be available in the
plugins/group_vars/all file for the user to uncomment. We missed
adding a few of those options to the file, so I've added them.
I also removed a section of outdated documentation that snuck
back in during a merge.

Change-Id: Ib5b19ebc02477a00765bc625612c7f9ae8ed0de3