Revised documentation

[tsnouidui]

From a user:

One thing which always bothered me though is the missing section 'Run an FMU created with SimulatorToFMU', because this is kind of hidden in 'outputs of SimulatorToFMU'. If you try to go through the simulation step by step you will usually try to run the example FMU after you create it in 4.1, but the explanation how to run it comes much later. I think most users try to run the example first (and skip the section on how to create a wrapper and model_description file), to split up the complexity of the progress a bit. Therefore, I think to create the example FMU and how to set the enviroment paths to run it and test it should come earlier in the documentation and the explanation on how to write your own wrapper and model_description file should come later.