message: Fix typo in python.rst
  In line 23 there was an extra closing brace.
diff: @@ -20,7 +20,7 @@ The linear regression is the most simple model
  in machine learning described by the following expression
  :math:`Y = XA + B`. We can see it as a function of three
  variables :math:`Y = f(X, A, B)` decomposed into
  -`y = Add(MatMul(X, A), B))`. That what's we need to represent
  +`y = Add(MatMul(X, A), B)`. That what's we need to represent
  with ONNX operators. The first thing is to implement a function
  with :ref:`ONNX operators <l-onnx-operators>`.
  ONNX is strongly typed. Shape and type must be defined for both
  