Improve the example code

[Hammster]

Currently, the example code gives you a good start but it sadly lets you hang on a point that can be really hard to get into. Especially if you have no solid knowledge about ECS.

Some Example that are missing or had me confused

• Example usage of delta time
• Example system to spawn new entities (Bullets maybe?)
• Working example of input handling that (maybe moving the kiwi left/right/up/down)
  • In the current example I was not able to get it any usable value out of it, the get_axis always returned 0.0
• Dead code, Shot, Player component for example

Most importantly the Kiwi is not a Kiwi, take this quick free pixel art of mine

[Hammster]

Also fixed the call for systems setup function in #6 🙂