added getting-started guide that uses Cubecell as an example. Pointed out areas that may be device specific or device different. Suggested any target device specific things would be in the device specific sample README's.
add associated screen capture pngs
added two Heltec CubeCell examples
added getting-started guide that uses Cubecell as an example. Pointed out areas that may be device specific or device different. Suggested any target device specific things would be in the device specific sample README's. add associated screen capture pngs added two Heltec CubeCell examples