Docs: pyplot.axes() should mention the aspect keyword argument

[edbrannin]

The docs for pyplot.axes make no mention of the aspect kwarg.

I only knew it would work based on Stack Overflow and the last code snippet in the docs for pyplot.pie.

[tacaswell]

@edbrannin Could you suggest what text should be added?

[edbrannin]

How about something like:

kwarg	Accepts	Description
aspect	Numbers	Aspect ratio for the plot: 1 is square, 1.3 is wide like an old TV, 0.5 is twice as tall as it is wide.

[tacaswell]

@edbrannin Could you put that in a pull request?

[edbrannin]

Thank you! Sorry I didn't get back to this sooner.