Add list of supported ATen ops by ONNX converter into torch.onnx page
This PR introduces a new documentation page with a list of supported ATen operators by the ONNX converter.
When `make html` (or similar) are called, a python script will generate a temporary CSV file inside the doc build folder with a list of operators/opsets currently supported by the PyTorch ONNX exporter. That CSV is used by Sphinx to build a HTML table using the same theme as the rest of the documentation.
That page is linked to the existing `onnx.rst`, including its table of contents.
@BowenBao @shubhambhokare1 Feel free to add more details on how the script cross reference onnx symbolics and aten operators list from torch jit api`
Below is the workflow for the changed pages:
The initial torch.onnx page was modified to add a link to the list of supported aten operators
![image](https://user-images.githubusercontent.com/5469809/159046387-c459bffc-c9b2-4fcb-8468-8181fdddf911.png)
The screen below highlights the text structure changes to the `ATen operartors` section
![image](https://user-images.githubusercontent.com/5469809/159046730-ccd1e594-c8e6-4b8d-a9ec-8bf6ad58a435.png)
Finally the new page with the list of supported operators is shown below
![image](https://user-images.githubusercontent.com/5469809/159046872-0d99b769-8b95-4c2b-99a9-a8cfdd0b6ecf.png)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74397
Approved by: https://github.com/garymm, https://github.com/malfet