Docs: proc: fix kernel version

Change the kernel version in table 1-2 from 3.20 to 4.1

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
Reviewed-by: Nathan Scott <nathans@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --cc Documentation/filesystems/proc.txt
Simple merge