Our documentation has pages for 4 go modules, 2 current and 2 obsolete
ones, but points only to one of them and directly to golang's docs page.

Add a sub-page where all 4 sub-pages for the modules are linked.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>