tut16 + re-structuring

Author: dario-coscia

tutorials/README.md

@@ -7,10 +7,10 @@ In this folder we collect useful tutorials in order to understand the principles
 | Description   | Tutorial |
 |---------------|-----------|
 Introduction to PINA for Physics Informed Neural Networks training|[[.ipynb](tutorial1/tutorial.ipynb), [.py](tutorial1/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial1/tutorial.html)]|
+How to build a `Problem` in PINA|[[.ipynb](tutorial16/tutorial.ipynb), [.py](tutorial16/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial16/tutorial.html)]|
 Introduction to PINA `Equation` class|[[.ipynb](tutorial12/tutorial.ipynb), [.py](tutorial12/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial12/tutorial.html)]|
+Building custom geometries with `DomainInterface` class|[[.ipynb](tutorial6/tutorial.ipynb), [.py](tutorial6/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial6/tutorial.html)]|
 PINA and PyTorch Lightning, training tips and visualizations|[[.ipynb](tutorial11/tutorial.ipynb), [.py](tutorial11/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial11/tutorial.html)]|
-Building custom geometries with PINA `Location` class|[[.ipynb](tutorial6/tutorial.ipynb), [.py](tutorial6/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial6/tutorial.html)]|
-
 
 ## Physics Informed Neural Networks
 | Description   | Tutorial  |