Remove the deprecated "giturl" option
Remove the deprecated "giturl" option

From openstackdocstheme 1.18.0, valid Git URLs can be retrieved by
openstackdocstheme[1], we do not need giturl option anymore.

[1] https://review.openstack.org/532163

Change-Id: I5ef41ade2ad4a74b74101e2b4710f6fd293e8f3c

openstack/searchlight,openstack/searchlight,openstack/searchlight