Merge pull request #24 from btsimonh/bipropellantref2

Add BiPropellant reference to readme

Author: btsimonh

README.md

@@ -97,3 +97,4 @@ If you need additional features like a boost button, have a look at the while(1)
 * [bobbycar-optimized firmware](https://github.com/larsmm/hoverboard-firmware-hack-bbcar)  based on this one with driving modes, acceleration ramps and some other features
 * [wheel chair](https://github.com/Lahorde/steer_speed_ctrl) controlled with a joystick or using a CC2650 sensortag to control it over  bluetooth with pitch/roll.
 * [TranspOtterNG](https://github.com/Jan--Henrik/transpOtterNG) TranspOtter is an open source semi self driving transportation platform based on hoverboard hardware
+* [BiPropellant](https://github.com/bipropellant) - fork which focusses on reliable machine control, but also retains HoverBoard functionality if desired.