Add base solution for exercise 6

README.md

model_examples/saxony.transportation_network

stgroup.mdsd.transportation_network.textgeneration/.project

...on_network.textgeneration/gen/documentation/overview.html

...mdsd.transportation_network.textgeneration/generation.egx

....transportation_network.textgeneration/scripts/asCard.egl

...portation_network.textgeneration/templates/t_overview.egl