Add hypervisor brief description on its concept and
how nova offer the ability to admin to interact with it;
Also add description for migraitons.
There is a doc about aggregates, so put the link
in general_info.rst.
blueprint complete-todo-in-api-concept-doc
Change-Id: I61f6999be62e3e689ca9bf8b28b08f6a0b4aa9df
Uses openstackdocstheme to match other content
Has a dependent change in project-config also so that
file will build to developer.openstack.org/compute
at https://review.openstack.org/#/c/231000/
Change-Id: Ic060a1e79e4b2f8695cb788ff4df018e0cfd3286