Bluetooth: Add documentation for Marvell Bluetooth driver

add btmrvl.txt to Documentation/

This patch incorporates a lot of comments given by
Nicolas Pitre <nico@marvell.com>. Many thanks to Nicolas Pitre.

Signed-off-by: Rahul Tank <rahult@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index d05737a..06b982a 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -82,6 +82,8 @@
 	- info on the Block I/O (BIO) layer.
 blockdev/
 	- info on block devices & drivers
+btmrvl.txt
+	- info on Marvell Bluetooth driver usage.
 cachetlb.txt
 	- describes the cache/TLB flushing interfaces Linux uses.
 cdrom/