Documentation/kmemcheck: update kmemcheck documentation

Kmemcheck configuration menu location correction in Documentation/
kmemcheck.txt

Signed-off-by: Libin <[e-mail]>
Acked-by: Rob Landley <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/kmemcheck.txt

···
 debugging a problem. This option is not mandatory, however, because it slows
 down the compilation process and produces a much bigger kernel image.
 
-Now the kmemcheck menu should be visible (under "Kernel hacking" / "kmemcheck:
-trap use of uninitialized memory"). Here follows a description of the
-kmemcheck configuration variables:
+Now the kmemcheck menu should be visible (under "Kernel hacking" / "Memory
+Debugging" / "kmemcheck: trap use of uninitialized memory"). Here follows
+a description of the kmemcheck configuration variables:
 
   o CONFIG_KMEMCHECK