add a known issue for lxc-1.0.0.beta3 and beyond for removeal of lxc-kill see #3844

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
Merge pull request #3864 from SvenDowideit/lxc-kill-script-workaround-doc

add a known issue for lxc-1.0.0.beta3 and beyond for removeal of lxc-kil...