KVM: s390: Clarify key argument for MEM_OP in api docs

Clarify that the key argument represents the access key, not the whole
storage key.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220221143657.3712481-1-scgl@linux.ibm.com
Fixes: 5e35d0eb ("KVM: s390: Update api documentation for memop ioctl")
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

Documentation/virt/kvm/api.rst

@@ -3763,7 +3763,7 @@ KVM_S390_MEMOP_F_INJECT_EXCEPTION is set.
 
 If the KVM_S390_MEMOP_F_SKEY_PROTECTION flag is set, storage key
 protection is also in effect and may cause exceptions if accesses are
-prohibited given the access key passed in "key".
+prohibited given the access key designated by "key"; the valid range is 0..15.
 KVM_S390_MEMOP_F_SKEY_PROTECTION is available if KVM_CAP_S390_MEM_OP_EXTENSION
 is > 0.