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>

pina/equation/equation.py

@@ -1,6 +1,7 @@
-""" Module """
+""" Module for Equation. """
 from .equation_interface import EquationInterface
 
+
 class Equation(EquationInterface):
 
     def __init__(self, equation):
@@ -11,7 +12,7 @@ class Equation(EquationInterface):
 
         :param equation: A ``torch`` callable equation to
             evaluate the residual.
-        :type equation: callable
+        :type equation: Callable
         """
         if not callable(equation):
             raise ValueError('equation must be a callable function.'
@@ -29,4 +30,4 @@ class Equation(EquationInterface):
         :return: The residual evaluation of the specified equation.
         :rtype: LabelTensor
         """
-        return self.__equation(input_, output_)
+        return self.__equation(input_, output_)