Drivers: hv: vmbus: document the VMBus sysfs files

The 4 sysfs files should be stable ABIs to the user space.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 9289ecb..cde3ece 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4957,6 +4957,7 @@
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	include/linux/hyperv.h
 F:	tools/hv/
+F:	Documentation/ABI/stable/sysfs-bus-vmbus
 
 I2C OVER PARALLEL PORT
 M:	Jean Delvare <jdelvare@suse.com>