Documentation for v0.1 version (#199)

* Adding Equations, solving typos
* improve _code.rst
* the team rst and restuctore index.rst
* fixing errors

---------

Co-authored-by: Dario Coscia <dariocoscia@dhcp-015.eduroam.sissa.it>

tests/test_model/test_residualfnn.py

@@ -2,21 +2,25 @@ import torch
 import pytest
 from pina.model import ResidualFeedForward
 
+
 def test_constructor():
     # simple constructor
     ResidualFeedForward(input_dimensions=2, output_dimensions=1)
 
     # wrong transformer nets (not 2)
     with pytest.raises(ValueError):
-        ResidualFeedForward(input_dimensions=2, output_dimensions=1, transformer_nets=[torch.nn.Linear(2, 20)])
+        ResidualFeedForward(input_dimensions=2,
+                            output_dimensions=1,
+                            transformer_nets=[torch.nn.Linear(2, 20)])
 
     # wrong transformer nets (not nn.Module)
     with pytest.raises(ValueError):
-        ResidualFeedForward(input_dimensions=2, output_dimensions=1, transformer_nets=[2, 2])
+        ResidualFeedForward(input_dimensions=2,
+                            output_dimensions=1,
+                            transformer_nets=[2, 2])
+
 
 def test_forward():
     x = torch.rand(10, 2)
     model = ResidualFeedForward(input_dimensions=2, output_dimensions=1)
     model(x)
-
-