tools/build_docs.sh generates the devstack.org website from the static
pages and generated pages created by running shocco against a DevStack
checkout.
Note that while this is the complete auto page generation of the
devstack.org site, pushing the content back to GitHub is limited
to those with push access to the current repo.
Partial-bug 1235626
Change-Id: I61dc3d56e4a4832a9ddd1904dd8af65c15a17e50