docs: Update pointer to networking information
docs: Update pointer to networking information

Commit 6fb5dd4fd804 removed docs/archnetwork.html.in, but
left behind a pointer to it in docs/formatnetwork.html.in.

Update it so that it points to the wiki, which contains
more detailed and recent information anyway.

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