Update ark docbook to 16.12

add infos about ark GSOC project
content from
http://mvlabat.github.io/ark-gsoc-2016/tasks/2016/08/17/finishing-my-gsoc-project.html
and
https://community.kde.org/GSoC/2016/StatusReports/Batyrenko_Vladyslav
add para about compression method for rar, 7z, zip
REVIEW:128883