Updated openstack/openstack
Project: openstack/taskflow  d6c2311efad00e10e34bf59696e6a0830a7de018

Rename additional to general/higher-level

The wiki really contains the general/overview and
higher-level information and the developer documentation
should reflect this (instead of just saying additional
documentation is located there).

Change-Id: I4ac58aac6ec61b11f4507a7c51973e0b492c5ade