UpSampling Operator Documentation is incomplete

[anirudhacharya]

The UpSampling operator documentation is incomplete - https://mxnet.incubator.apache.org/api/python/ndarray/ndarray.html?highlight=upsam#mxnet.ndarray.UpSampling

It does not show num_args as a parameter - https://github.com/apache/incubator-mxnet/blob/master/src/operator/nn/upsampling-inl.h#L50 . And in bilinear mode the operator expects two inputs - data and weight. Even that is not specified in the documentation.

This can cause confusion like in here - #13073

[anirudhacharya]

@mxnet-label-bot [Operator, Doc, Bug]

[apeforest]

@mxnet-label-bot [Call for Contribution, Good First Issue]