kgdb,docs: Update the kgdb docs to include kms

Update the kgdb docs to include information about kernel mode setting support.

[Randy Dunlap <rdunlap@xenotime.net>: grammatical corrections]

CC: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2b2407d..0e4f39f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1143,9 +1143,12 @@
 	kgdboc=		[KGDB,HW] kgdb over consoles.
 			Requires a tty driver that supports console polling,
 			or a supported polling keyboard driver (non-usb).
-			Serial only format: <serial_device>[,baud]
-			keyboard only format: kbd
-			keyboard and serial format: kbd,<serial_device>[,baud]
+			 Serial only format: <serial_device>[,baud]
+			 keyboard only format: kbd
+			 keyboard and serial format: kbd,<serial_device>[,baud]
+			Optional Kernel mode setting:
+			 kms, kbd format: kms,kbd
+			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
 
 	kgdbwait	[KGDB] Stop kernel execution and enter the
 			kernel debugger at the earliest opportunity.