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/__init__.py

@@ -1,21 +1,13 @@
 __all__ = [
-    'PINN',
-    'Trainer',
-    'LabelTensor',
-    'Plotter',
-    'Condition',
-    'Location',
-    'CartesianDomain'
+    'PINN', 'Trainer', 'LabelTensor', 'Plotter', 'Condition',
+    'SamplePointDataset', 'SamplePointLoader'
 ]
 
 from .meta import *
 from .label_tensor import LabelTensor
-from .solvers.pinn import PINN
+from .solvers.solver import SolverInterface
 from .trainer import Trainer
 from .plotter import Plotter
 from .condition import Condition
-from .geometry import Location
-from .geometry import CartesianDomain
-
 from .dataset import SamplePointDataset
-from .dataset import SamplePointLoader
+from .dataset import SamplePointLoader