Add docs about the WiFi-Box in this repo's wiki

[companje]

https://github.com/Doodle3D/WiFi-Box/wiki

[companje]

This is a drawing explaining how the WiFi-Box connects drawing apps on different devices over WiFi to 3D-printers through USB.

PNG:

[companje]

This image explains shows how a drawing made in the Doodle3D app is send to the WiFi-Box which is connected through USB to a 3D-printer.

[peteruithoven]

Most docs currently live here:
http://www.doodle3d.com/help/wiki/firmware
http://www.doodle3d.com/help/wiki/serverside

This issue is about moving such docs to this repo's wiki?

[companje]

Yes, eventually I would like to move all documentation from http://www.doodle3d.com/help/wiki to the wikis of the corresponding repository (ie. all print3d related info to the print3d github wiki etc).