KVM: s390: change help text of guest Kconfig

The current help text for CONFIG_S390_GUEST is not very helpful.
Lets add more text.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/s390/Kconfig

@@ -565,13 +565,16 @@ config ZFCPDUMP
 	  Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
 
 config S390_GUEST
-bool "s390 guest support (EXPERIMENTAL)"
+bool "s390 guest support for KVM (EXPERIMENTAL)"
 	depends on 64BIT && EXPERIMENTAL
 	select VIRTIO
 	select VIRTIO_RING
 	select VIRTIO_CONSOLE
 	help
-	  Select this option if you want to run the kernel under s390 linux
+	  Select this option if you want to run the kernel as a guest under
+	  the KVM hypervisor. This will add detection for KVM as well  as a
+	  virtio transport. If KVM is detected, the virtio console will be
+	  the default console.
 endmenu
 
 source "net/Kconfig"