docs: remove Google+ link from page footer
docs: remove Google+ link from page footer

Google is shutting down Google+, with no replacement, in the very near
future so we are losing the Libvirt community group there.

Reviewed-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

fabianfreyer/libvirt,andreabolognani/libvirt,eskultety/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,nertpinx/libvirt,crobinso/libvirt,eskultety/libvirt,jardasgit/libvirt,zippy2/libvirt,jfehlig/libvirt,zippy2/libvirt,andreabolognani/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,eskultety/libvirt,andreabolognani/libvirt,olafhering/libvirt,jardasgit/libvirt,olafhering/libvirt,jardasgit/libvirt,jfehlig/libvirt,zippy2/libvirt,nertpinx/libvirt,jardasgit/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,olafhering/libvirt,andreabolognani/libvirt,libvirt/libvirt,libvirt/libvirt,andreabolognani/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,crobinso/libvirt,crobinso/libvirt,nertpinx/libvirt,libvirt/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,zippy2/libvirt,eskultety/libvirt