remove not up-to-date design.txt
remove not up-to-date design.txt

it can be found at:
https://github.com/neutrinolabs/xrdp/wiki/XRDP-Architecture-Overview

metalefty/xrdp,metalefty/xrdp,metalefty/xrdp,neutrinolabs/xrdp,neutrinolabs/xrdp,neutrinolabs/xrdp