Documentation/sysctl/user.txt: fix typo

Fix 'documetation' to 'documentation'

Link: http://lkml.kernel.org/r/CAKW4uUxRPZz59aWAX8ytaCB5=Qh6d_CvAnO7rYq-6NRAnQJbDA@mail.gmail.com
Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Kosina <trivial@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/sysctl/user.txt

@@ -3,7 +3,7 @@ Documentation for /proc/sys/user/*	kernel version 4.9.0
 
 ==============================================================
 
-This file contains the documetation for the sysctl files in
+This file contains the documentation for the sysctl files in
 /proc/sys/user.
 
 The files in this directory can be used to override the default