[S390] cio: update documentation.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/Documentation/s390/driver-model.txt b/Documentation/s390/driver-model.txt
index 62c0823..77bf450 100644
--- a/Documentation/s390/driver-model.txt
+++ b/Documentation/s390/driver-model.txt
@@ -239,6 +239,9 @@
 
 type - The physical type of the channel path.
 
+shared - Whether the channel path is shared.
+
+cmg - The channel measurement group.
 
 3. System devices
 -----------------