tox.ini: Whitelist rm
tox.ini: Whitelist rm

Remove noise from execution, whitelist rm command.

Change-Id: I270d7e98fe857501fa6ac1a38f6ff928ea0192de

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