Add description to package.json
Add description to package.json

This should fix the ugly broken markdown at the top of npm
Tyriar/xterm.js,cjordog/NRLWebsite,xtermjs/xterm.js,Tyriar/xterm.js,akalipetis/xterm.js,akalipetis/xterm.js,cjordog/NRLWebsite,sourcelair/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,sourcelair/xterm.js,cjordog/NRLWebsite,xtermjs/xterm.js,sourcelair/xterm.js,akalipetis/xterm.js,cjordog/NRLWebsite,xtermjs/xterm.js,akalipetis/xterm.js