Add minimal documentation about kuka_drivers

[resizoltan]

I mean the Wiki page on GitHub: https://github.com/kroshu/ros2_kuka_sunrise/wiki
I think this is a good compromise between having just some markdown files (which is a bit more hassle to navigate for users) and a separate documentation webpage (which is more work for us to set up, but in the future it might be the best way to go - see for example https://control.ros.org/getting_started.html )

[resizoltan]

Hey, I pushed an initial documentation to feature/prepare-for-open-collab. I guess it should be enough for now.
@kovacsge11 it would be nice if you could double-check the quick-start-guide
@Groebehavn if you have time sometime, you could take a look at the ros2_control related section and we could discuss whether you agree

[kovacsge11]

Done.

[Groebehavn]

ROS Wiki states, that: "The ROS Wiki is for ROS 1." There is a "rolling documentation" for ROS2. Probably uploading to the Wiki might not be necessary. What's your opinion?

[resizoltan]

So the idea is we just write the documentation in our favourite desktop md editor and can track it via git but also make it visible on the Wiki page where navigation is somewhat better

[Groebehavn]

Okay, misunderstood. Sounds good! :)

[kovacsge11]

The quick-start seems nice, although the teleop-guided-robot package is missing, I'll add it.