Documentation bug: isinf has signature-description inconsistency

Description

There is a signature-description inconsistency in the document of the following 3 APIs. The Parameter section stated that there should be a parameter input, but it is not accepted by the API.

• mxnet.ndarray.contrib.isinf: https://mxnet.apache.org/versions/1.6/api/python/docs/api/ndarray/contrib/index.html#mxnet.ndarray.contrib.isinf
• mxnet.ndarray.contrib.isfinite: https://mxnet.apache.org/versions/1.6/api/python/docs/api/ndarray/contrib/index.html#mxnet.ndarray.contrib.isfinite
• mxnet.ndarray.contrib.isnan: https://mxnet.apache.org/versions/1.6/api/python/docs/api/ndarray/contrib/index.html#mxnet.ndarray.contrib.isnan

Error Message

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: isinf() got an unexpected keyword argument 'input'

To Reproduce

(If you developed your own code, please provide a short script that reproduces the error. For existing examples, please provide link.)

import mxnet
mxnet.ndarray.contrib.isinf(input=mxnet.nd.array([1]))

Environment

We recommend using our script for collecting the diagnositc information. Run the following command and paste the outputs below:

curl --retry 10 -s https://raw.githubusercontent.com/dmlc/gluon-nlp/master/tools/diagnose.py | python

# paste outputs here

OS: ubuntu 18.04 Python: 3.7.6 pip: 20.0.2 numpy: 1.18.5 mxnet: 1.6.0