Documentation: Add nested versions of mutex locks to docs

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/Documentation/mutex-design.txt b/Documentation/mutex-design.txt
index 51f9351..aa60d1f 100644
--- a/Documentation/mutex-design.txt
+++ b/Documentation/mutex-design.txt
@@ -133,4 +133,6 @@
  int  mutex_trylock(struct mutex *lock);
  void mutex_unlock(struct mutex *lock);
  int  mutex_is_locked(struct mutex *lock);
-
+ void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
+ int  mutex_lock_interruptible_nested(struct mutex *lock,
+                                      unsigned int subclass);