input: Documentation: corrections for notifier.rst

Add 'ledstate' to the keyboard_notifier_param struct info and tell
which header file contains that struct.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/20210302223523.20130-7-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/input/notifier.rst

@@ -4,11 +4,12 @@ Keyboard notifier
 
 One can use register_keyboard_notifier to get called back on keyboard
 events (see kbd_keycode() function for details).  The passed structure is
-keyboard_notifier_param:
+keyboard_notifier_param (see <linux/keyboard.h>):
 
 - 'vc' always provide the VC for which the keyboard event applies;
 - 'down' is 1 for a key press event, 0 for a key release;
 - 'shift' is the current modifier state, mask bit indexes are KG_*;
+- 'ledstate' is the current LED state;
 - 'value' depends on the type of event.
 
 - KBD_KEYCODE events are always sent before other events, value is the keycode.