textproc/py-openstackdocstheme: Update to 2.2.7

• Remove the DOCS option as the documentation contains mostly references to external sites and isn't really useful for offline use.

• Also update the RUN_DEPENDS of consumer textproc/py-os-api-ref to avoid conflicting dependencies and bump its PORTREVISION accordingly.

Changelog:

https://github.com/openstack/openstackdocstheme/compare/1.21.0...2.2.7