Thanks for the PR, but I don't think there's anything to be changed here, except perhaps clarifying (generally) that examples must be run with the corresponding version of Matplotlib (and thus mpl master examples -> mpl master).

I guess if you restrict this PR to adding a description, it would still be an improvement.

I was planning on tackling a couple of excercises missign descriptions as stated on #8921. Would it be better to close this PR and then do a new one with only the descriptions but add more of them?

Sure, whatever suits you better.
While walking through examples, you can also add references as discussed in #10974.

I'm having the same issue, I'm wondering why this wasn't merged in

@PredatorFeesh the problem was that I was using the stable version of matplotlib which is the version you get from doing your pip install. But this example is done on the dev branch (master) which is further ahead with some functionality that changed how the examples behave.

You need to either checkout the branch of the version you are using locally and get the examples from there, or download and build the dev branch and then run the examples with that branch.

If you use the matplotlib 3.0+ examples with matplotlib 2.4 for example, then this example won't run

@PredatorFeesh you can check your version of Matplotlib using

import matplotlib
matplotlib.__version__

in the environment in which you're running the example. Sorry, completely forgot about that check (sometimes the installs of the dev version don't stick).

I'm running version 3.0.3, which is what pip installs.

Sorry, missed that - you need to install off your branch. Instructions starting around https://matplotlib.org/devel/gitwash/set_up_fork.html