Updated OnnxScoringEstimator's documentation

[antoniovs1029]

PR #4919 changed the way users should work with the Onnxruntime's nugets, now they should include either Onnxruntime or Onnxruntime.Gpu nuget along the OnnxTransformer one.

I also updated a couple of other things that weren't right anymore.

Please, let me know it I should update the docs anywhere else.

Fixes #4872

[kere-nel]

What's the reason for changing from "used" to "desired"?

[antoniovs1029]

I just found it confusing because you can't use GPU processing without the nuget, so you should install it before it is "used".

Do you think it's clearer with 'used'?

[kere-nel]

hmm would "available" be a better word? Doesn't ml.net fail if there isn't a GPU, but you try to use the nuget?

[luisquintanilla]

Suggested change

	/// | Required NuGet in addition to Microsoft.ML | Microsoft.ML.OnnxTransformer (always), either Microsoft.ML.OnnxRuntime 1.2.0 (for CPU processing) or Microsoft.ML.OnnxRuntime.Gpu 1.2.0 (only if GPU processing is desired) |
	/// | Required NuGet in addition to Microsoft.ML | Microsoft.ML.OnnxTransformer (always), either Microsoft.ML.OnnxRuntime 1.2.0 (for CPU processing) or Microsoft.ML.OnnxRuntime.Gpu 1.2.0 (for GPU processing if GPU is available) |

[natke]

Luis' suggestion is good. Can I clarify what happens if:
a) you install both
b) you install the GPU nuget and you don't don't run with a GPU?

[antoniovs1029]

So I've accepted Luis' suggestion 😄

Regarding your questions, @natke
a) I hadn't tested the case of installing both, because I was told by @harishsk that users should install only one. I have just made a quick test installing both on my laptop (without GPU), and it doesn't throw any errors when running, so I guess it is simply using the non-GPU nuget. I am having some troubles using my remote GPU computer, so I haven't had the chance to test it there.
b) If I install the GPU nuget on a computer without GPU, the following error is thrown when running the code:

    System.TypeInitializationException : The type initializer for 'Microsoft.ML.OnnxRuntime.NativeMethods' threw an exception.
    ---- System.DllNotFoundException : Unable to load DLL 'onnxruntime' or one of its dependencies: The specified module could not be found. (Exception from HRESULT: 0x8007007E)

Reason for this is that the onnxruntime DLL has a dependency on CUDA and CuDNN, so if those aren't installed, it can't load onnxruntime either.

[antoniovs1029]

I have tested this now on my remote GPU. And when installing both nugets, the GPU nuget gets ignored when running a sample code, it throws the exception that is expected when trying to use the GPU feature without the GPU nuget:
Unable to find an entry point named 'OrtSessionOptionsAppendExecutionProvider_CUDA' in DLL 'onnxruntime'

So in general it seems that when installing both nugets, the GPU one gets completely ignored.

[luisquintanilla]

Looks good. Added a suggestion.

[luisquintanilla]

Suggested change

	/// | Required NuGet in addition to Microsoft.ML | Microsoft.ML.OnnxTransformer (always), either Microsoft.ML.OnnxRuntime 1.2.0 (for CPU processing) or Microsoft.ML.OnnxRuntime.Gpu 1.2.0 (only if GPU processing is desired) |
	/// | Required NuGet in addition to Microsoft.ML | Microsoft.ML.OnnxTransformer (always), either Microsoft.ML.OnnxRuntime 1.2.0 (for CPU processing) or Microsoft.ML.OnnxRuntime.Gpu 1.2.0 (for GPU processing if GPU is available) |

[natke]

Luis' suggestion is good. Can I clarify what happens if:
a) you install both
b) you install the GPU nuget and you don't don't run with a GPU?

[natke]

Added some minor re-wording

[antoniovs1029]

/azp run

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