readme: add nixos package
readme: add nixos package

SirCmpwn/sway,ascent12/sway,sleep-walker/sway,4e554c4c/sway,taiyu-len/sway,1ace/sway,1ace/sway,sleep-walker/sway,johalun/sway,mikkeloscar/sway,ascent12/sway,ascent12/sway,mikkeloscar/sway,taiyu-len/sway,1ace/sway,taiyu-len/sway,4e554c4c/sway,ptMuta/sway