Update writing_layers.rst

Fix broken link

Author: nicolasvasilache

docs/source/framework/pytorch_integration/writing_layers.rst

@@ -200,7 +200,7 @@ functions. For example, assume one wants to use :code:`fmax` CUDA function in TC
         O = T.relu(torch.randn(100, 128, device='cuda'))
 
 TC only supports a subset of built-in CUDA functions.
-Built-in functions supported in TC are listed in `this file <https://github.com/facebookresearch/TensorComprehensions/blob/master/tc/core/libraries.h#L67>`_.
+Built-in functions supported in TC are listed in `this file <https://github.com/facebookresearch/TensorComprehensions/blob/master/tc/core/cuda/cuda_libraries.h#L67>`_.
 Documentation
 for these functions is available as part of the official `CUDA documentation <http://docs.nvidia.com/cuda/cuda-math-api/group__CUDA__MATH__SINGLE.html#group__CUDA__MATH__SINGLE>`_.