[S390] cio: Add s390-drivers book.

s390-drivers is generated using the docbook comments. It should
eventually supersede Documentation/s390/cds.txt.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index 08687e4..1a7f530 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -11,7 +11,7 @@
 	    procfs-guide.xml writing_usb_driver.xml \
 	    kernel-api.xml filesystems.xml lsm.xml usb.xml \
 	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
-	    genericirq.xml
+	    genericirq.xml s390-drivers.xml
 
 ###
 # The build process is as follows (targets):