cgroups: fix documentation

Correct the cgroups documentation to reflect the correct file names.

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Dhaval Giani

Documentation/cgroups.txt

@@ -310,8 +310,8 @@ and then start a subshell 'sh' in that cgroup:
   cd /dev/cgroup
   mkdir Charlie
   cd Charlie
-  /bin/echo 2-3 > cpus
-  /bin/echo 1 > mems
+  /bin/echo 2-3 > cpuset.cpus
+  /bin/echo 1 > cpuset.mems
   /bin/echo $$ > tasks
   sh
   # The subshell 'sh' is now running in cgroup Charlie