Add module mapping pystencils_autodiff -> pystencils.autodiff

src/pystencils_autodiff/__init__.py

+import sys
+
 import pystencils_autodiff.backends  # NOQA
 from pystencils_autodiff._field_to_tensors import (  # NOQA
     tf_constant_from_field, tf_placeholder_from_field, tf_scalar_variable_from_field,
@@ -15,3 +17,6 @@ __all__ = ['backends',
            "tf_constant_from_field", " tf_placeholder_from_field",
            "tf_scalar_variable_from_field", " tf_variable_from_field",
            "torch_tensor_from_field"]
+
+sys.modules['pystencils.autodiff'] = pystencils_autodiff
+sys.modules['pystencils.autodiff.backends'] = pystencils_autodiff.backends

src/pystencils_autodiff/backends/__init__.py

+"""
+Backends for operators to support automatic Differentation
+
+Currently, we can use pystencils' JIT compilation to register
+a Torch or a Tensorflow operation or we can compile a static
+library to be directly loaded into Torch/Tensorflow.
+"""
 
 AVAILABLE_BACKENDS = ['tensorflow', 'torch', 'tensorflow_cpp', 'torch_native']