Ep3: Improve Dataset image

[izmear]

In episode 3 (http://swcarpentry.github.io/matlab-novice-inflammation/03-plotting/index.html) when we look at averaging the dataset, it would be good to remind the learners of what the rows and columns are. It has been two episodes since the set was introduced and used.

The image from the python course is far more instructive than the current image in the MATLAB course:

Would it be possible to do a simple replace?

Without knowing that columns are days and rows are patients it is difficult for grasp the dataset.

[gcapes]

This is a good idea. The images would need some tweaking or at least trimming to remove the python code elements.