Markdown parsing error in NovoGrad documentation page

[seungjaeryanlee]

The documentation page of NovoGrad has a broken Markdown link shown below:

I suspect this is because only the first line of the docstring is used for the first line of the documentation page. In the docstring (shown below), the link spans multiple lines.

addons/tensorflow_addons/optimizers/novograd.py

Lines 26 to 28 in 5f74697

	"""The NovoGrad Optimizer was first proposed in [Stochastic Gradient
	Methods with Layerwise Adaptvie Moments for training of Deep
	Networks](https://arxiv.org/pdf/1905.11286.pdf)

The simplest solution would be to edit the docstring so that there is a one-line summary for the first line with a paper link after the newline. One example would be LAMB's documentation page. I will create a PR with this solution.

[WindQAQ]

Feel free to request my review after submitting the PR 😃 It's also appreciated that you can add testable docstring for it. See #2066 for more details.

[seungjaeryanlee]

I'll integrate doctest in a separate PR once I understand how everything works. Thanks for the suggestion and the link to the issue!