Add mISDN driver

mISDN is a new modular ISDN driver, in the long term it should replace
the old I4L driver architecture for passiv ISDN cards.

Signed-off-by: Karsten Keil <kkeil@suse.de>

Documentation/isdn/README.mISDN

@@ -0,0 +1,6 @@
+mISDN is a new modular ISDN driver, in the long term it should replace
+the old I4L driver architecture for passiv ISDN cards.
+It was designed to allow a broad range of applications and interfaces
+but only have the basic function in kernel, the interface to the user
+space is based on sockets with a own address family AF_ISDN.
+