Update the documents, making the following changes:
* Reference Fedora 24 instead of the outdated Fedora 21
* Don't reference the removed 'rejoin-stack' script
* Let devstack do as much work for us as possible (NUMATopologyFilter)
* Don't overcomplicate anything (installing emacs, using non-standard
devstack install dir)
* Use '$' prefix for non-root commands
* Update XML with latest examples
* Use the 'openstack' client, rather than the 'nova' client
* Random formatting fixes
...and, finally, stop hating on poor, innocent vi.
Change-Id: Idc89a5c0617ccf7044e1cfc2b5d7f5ff4004b5bf