Add rtty to the real-world uses section of README
Add rtty to the real-world uses section of README

A reverse proxy WebTTY. It is composed of the client and the server.

Signed-off-by: Jianhui Zhao <8d133ac9c3777a160289d8ad8989d4d8f2aa6571@gmail.com>

akalipetis/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,akalipetis/xterm.js,sourcelair/xterm.js,akalipetis/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,akalipetis/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,sourcelair/xterm.js