Fix local niceness checks with RST
Fix local niceness checks with RST

Add doc/*/build also to doc8 ignore list, so that locally running
tox -e checkniceness works if you build RST manuals locally.

Change-Id: I8e3e3e201bf60c27e791f6c764ab3514b3337e7a

gongysh2004/openstack-manual,saeki-masaki/openstack-manuals,kairoaraujo/openstack-manuals,saeki-masaki/openstack-manuals,potsmaster/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals