Flesh out the readme

[gavanderhoorn]

The readme in this repository is currently almost empty.

The readme of rxros seems to contain some information related to the examples (such as this and this section), and it would be good to migrate that to the readme here.

Furthermore, a How to install section, mentioning the .rosinstall file, would probably be needed.

[henrik7264]

@gavanderhoorn and @wasowski I will soon start on this issue. I have an idea of creating a fully working Lego/BrickPi3 robot based on RxROS, i.e. a project with launch files, maps, rviz files etc.
Do you think this should be part of the ros_examples project or should this be a new project we will start up later?

[gavanderhoorn]

If it's going to be this extensive I would probably suggest to not host this here, as these packages are supposed to be relatively simple examples for getting into RxROS -- or at least I understood that was the intention.

[gavanderhoorn]

That doesn't mean that the readme here doesn't still need to be updated of course ;)