Update python doc (#5803)

Several improvement and adjustments to the Python documentation

- applied autopep8
- add summary example
- use references to reference other classes and methods

docs/rips/grid.py

@@ -11,10 +11,11 @@ import rips.generated.Grid_pb2_grpc as Grid_pb2_grpc
 
 
 class Grid:
-    """Grid Information. Not meant to be constructed separately
-
-    Create Grid objects using methods on Case: Grid() and Grids()
+    """Grid Information. Created by methods in Case
+    :meth:`rips.case.grid()`
+    :meth:`rips.case.grids()`
     """
+
     def __init__(self, index, case, channel):
         self.__channel = channel
         self.__stub = Grid_pb2_grpc.GridStub(self.__channel)
@@ -33,7 +34,6 @@ class Grid:
             Grid_pb2.GridRequest(case_request=case_request,
                                  grid_index=self.index)).dimensions
 
-
     def cell_centers_async(self):
         """The cells center for all cells in given grid async.