DOC: Update Matplotlib Colormaps documentation link in chart visualization #43624
- [x] closes #43624 

Fixes: Fixed a chart visualization coiormap section link that linked to an outdated version of matplotlib. Now links to a [stable version](https://matplotlib.org/stable/gallery/color/colormap_reference.html#sphx-glr-gallery-color-colormap-reference-py).

Rather than hardcoding the url, why not use an intersphinx reference here? > 
> 
> Rather than hardcoding the url, why not use an intersphinx reference here?

I don't know what intersphinx is, could you elaborate a little bit more? https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html

you can reference the label they use for that section so it will still resolve properly if they reorganize their site in the future I've done some research and in order to use intersphinx, both docs must use intersphinx as extension to their documentation and I don't know if either pandas or matplotlib use it. https://github.com/pandas-dev/pandas/blob/master/doc/source/conf.py#L429-L439 Where can I find the label they use for that section? And wouldn't it be more useful to create a new issue to change all the documentation to use intersphinx, rather than a single link/element?  > Where can I find the label they use for that section?

If you click "show page source" on the matplotlib docs (and most sphinx sites) you can see the raw rst. Right above the H1 element there's a reference target:

```
.. _sphx_glr_gallery_color_colormap_reference.py:
```

> And wouldn't it be more useful to create a new issue to change all the documentation to use intersphinx, rather than a single link/element?

(I am not a pandas maintainer and have no opinion on the best path forward, just dropping by with a suggestion). I'd be happy merging this as is since a definite improvement, but will wait a bit to see if others weigh in.

Thanks for the idea @mwaskom - if you wouldn't mind opening an issue with the suggestion of using more intersphinx (and the related advantages), that would be awesome > Where can I find the label they use for that section? And wouldn't it be more useful to create a new issue to change all the documentation to use intersphinx, rather than a single link/element?

agreed, I would just merge as is and open an issue for intersphinx, Perhaps it could be part of a beginners sprint or soemthing. thanks @ricardobohadana  Thank you!