Documentation: fix locking rt-mutex doc refs

Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/locking/rt-mutex-design.txt

@@ -8,7 +8,7 @@ RT-mutex implementation design
 
 This document tries to describe the design of the rtmutex.c implementation.
 It doesn't describe the reasons why rtmutex.c exists. For that please see
-Documentation/rt-mutex.txt.  Although this document does explain problems
+Documentation/locking/rt-mutex.txt.  Although this document does explain problems
 that happen without this code, but that is in the concept to understand
 what the code actually is doing.
 

Documentation/pi-futex.txt

@@ -119,4 +119,4 @@ properties of futexes, and all four combinations are possible: futex,
 robust-futex, PI-futex, robust+PI-futex.
 
 More details about priority inheritance can be found in
-Documentation/rt-mutex.txt.
+Documentation/locking/rt-mutex.txt.