docs: fix encryption format attribute in example
docs: fix encryption format attribute in example

The correct attribute name is 'format', not 'type'.

https://bugzilla.redhat.com/show_bug.cgi?id=1139910

nertpinx/libvirt,taget/libvirt,fabianfreyer/libvirt,eskultety/libvirt,rlaager/libvirt,libvirt/libvirt,agx/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,datto/libvirt,eskultety/libvirt,zippy2/libvirt,eskultety/libvirt,VenkatDatta/libvirt,zippy2/libvirt,andreabolognani/libvirt,shugaoye/libvirt,rlaager/libvirt,elmarco/libvirt,crobinso/libvirt,andreabolognani/libvirt,rlaager/libvirt,jfehlig/libvirt,nertpinx/libvirt,libvirt/libvirt,taget/libvirt,jardasgit/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,crobinso/libvirt,rlaager/libvirt,agx/libvirt,eskultety/libvirt,datto/libvirt,shugaoye/libvirt,taget/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,olafhering/libvirt,andreabolognani/libvirt,agx/libvirt,agx/libvirt,olafhering/libvirt,datto/libvirt,zippy2/libvirt,taget/libvirt,elmarco/libvirt,nertpinx/libvirt,elmarco/libvirt,andreabolognani/libvirt,datto/libvirt,jardasgit/libvirt,nertpinx/libvirt,agx/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,andreabolognani/libvirt,zippy2/libvirt,datto/libvirt,taget/libvirt,crobinso/libvirt,olafhering/libvirt,elmarco/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,olafhering/libvirt,crobinso/libvirt,VenkatDatta/libvirt,rlaager/libvirt,eskultety/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,jfehlig/libvirt,nertpinx/libvirt,libvirt/libvirt,elmarco/libvirt,libvirt/libvirt