[doc] Differentiate between test, tutorial/documented, tutorial/undocumented
Currently we have two general "getting started tutorials", however many of our _tests_ are also thought of tutorials as they demonstrate a certain model.
I suggest to distinguish between _tests_ in the _test_ -folder that are specifically designed to test certain features and are small/run rather fast, and _tutorials_ in the _tutorial_-folder that are designed to show a certain feature, e.g. how to use the tensor grid factory in a Richards model to refine towards the soil top. I further suggest to create two new subfolders _documented_ and _undocumented_ where all _documented tutorials_ have a detailed latex/markdown problem and feature description. In the future, a number of maybe 10 such documented tutorials would be nice. All tutorials in undocumented can potentially become documented in the future.
Of course tutorials should also tested by the automated build system.
issue