Sort asending for companies in readme and add Nutanix
Sort asending for companies in readme and add Nutanix

Sorted the company list in the readme asending and added Nutanix to the list of users
xtermjs/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,xtermjs/xterm.js,sourcelair/xterm.js