The Large Scale SIG has started to publish their documentation at [0],
migrating content from the Wiki[1]. Add a link to the main landing page
and also add the repo to the _IGNORED_REPOS list in www-generator.py,
since it doesn't use the /latest/ patch as it is branchless and not
release-specific.
[0] https://docs.openstack.org/large-scale/index.html
[1] https://wiki.openstack.org/wiki/Large_Scale_SIG
Change-Id: Ie7f297615d746f36f24e63ee3f25b4938e6f45e3
9f58d2e715