[ctrlsf][vim] Search String by using ctrlsf

1. Install package “ack”
sudo pacman -S ack

1. Edit ~/.vimrc or ~/.vim/vimrc
   map :CtrlSF

under vim

:CtrlSF <search string which you want>

Reference:
每日vim插件–代码搜索ack.vim/ag/ctlsf.vim
vim每日插件之CtrlSF