Documentation: missing proc/$PID/stat field

There's a missing field in the /proc/$PID/stat output documented in
Documentation/filesystems/proc.txt.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 194c8f3..0b1b0c0 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -216,6 +216,7 @@
   priority      priority level
   nice          nice level
   num_threads   number of threads
+  it_real_value	(obsolete, always 0)
   start_time    time the process started after system boot
   vsize         virtual memory size
   rss           resident set memory size