KVM: doc: Fix typo in doc/virtual/kvm

Correct spelling typo in Documentations/virtual/kvm

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>