Added Codevolve.com to README
Added Codevolve.com to README

We use xterm.js for our courses at Codevolve.
Tyriar/xterm.js,sourcelair/xterm.js,xtermjs/xterm.js,akalipetis/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,cjordog/NRLWebsite,xtermjs/xterm.js,akalipetis/xterm.js,xtermjs/xterm.js,akalipetis/xterm.js,cjordog/NRLWebsite,Tyriar/xterm.js,Tyriar/xterm.js,cjordog/NRLWebsite,Tyriar/xterm.js,akalipetis/xterm.js,sourcelair/xterm.js,sourcelair/xterm.js,cjordog/NRLWebsite,Tyriar/xterm.js,sourcelair/xterm.js