add Arch Linux package info and rewrite install section
add Arch Linux package info and rewrite install section

anthrotype/sile,neofob/sile,simoncozens/sile,anthrotype/sile,anthrotype/sile,alerque/sile,neofob/sile,simoncozens/sile,neofob/sile,WAKAMAZU/sile_fe,simoncozens/sile,WAKAMAZU/sile_fe,WAKAMAZU/sile_fe,WAKAMAZU/sile_fe,alerque/sile,alerque/sile,alerque/sile,simoncozens/sile,neofob/sile,anthrotype/sile