Add detailed example workflows for spatial optimization in the README

[apawlik]

No description provided.

[heralex]

Yes, I certainly want to integrate the Optimisation HowTo content to the Documentation. What is still missing is a sample model of how to integrate the optimisation into a LUMASS modelling workflow and how to make the *.los files more dynamic. There will also be information on the new GA-based optimisation that will be available soon.