Adding narrative to the datasets

[mike-ivs]

As mentioned in #909 (and related to #887 and #179), this PR aims to introduce a narrative around the synthetic inflammation datasets used throughout the Lesson.

Doing so will hopefully help frame the lesson with a more realistic scenario to show how programming can help speed up data science/research/etc, as well as clarifying a few sections in the lesson that make reference to trends in the inflammation data, which otherwise have no context.

The narrative was created for a "condensed" data-driven tutorial that I gave a few weeks ago, and as such it could benefit from additional input rather than just my own thoughts. I'm more than happy to chop/change/remove/add things as desired, but hopefully this provides a meaningful contribution to the lesson and helps give context to the data.

[ldko]

@maxim-belkin I think this pull request looks good to close #909 and to close #179 and helps with #887. The only issue I noticed with it is it introduces long line warnings when running make lesson-check-all for a couple episodes.

@mike-ivs , thanks for submitting this. I think it will help a lot of instructors and learners better go along with the lesson. Where possible we try to keep lines from exceeding 100 characters in length. There are just a few places where your changes went over that. Perhaps you could break them up?

./_episodes/03-matplotlib.md: Line(s) too long: 34, 35, 38
./_episodes/06-files.md: Line(s) too long: 123

[mike-ivs]

@ldko thanks for the feedback, I've shortened those lines now along with a couple more that were very much on the limit.

[maxim-belkin]

Thank you for this excellent contribution, Mike! I found myself saying "take that, Dr. Maverick" while reading this, so... great work! I think this contribution closes #909 and partially #887 (I'll create an issue to update episode 1 with examples that are more relevant to the inflammation data / story).

Thanks, Mike! And thank you Lauren for pinging me!