KVM: nVMX: Document 'nested' parameter

Add documentation of the new 'nested' parameter to
'Documentation/kernel-parameters.txt'.

Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

Documentation/kernel-parameters.txt

@@ -1181,6 +1181,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
 			Default is 1 (enabled)
 
+	kvm-intel.nested=
+			[KVM,Intel] Enable VMX nesting (nVMX).
+			Default is 0 (disabled)
+
 	kvm-intel.unrestricted_guest=
 			[KVM,Intel] Disable unrestricted guest feature
 			(virtualized real and unpaged mode) on capable