Add short section to the overview chapter covering the sample code

[hollasch]

In particular, we should stress that our code is a toy implementation, isn't a recommended C++ implementation, leaves a lot of features on the table, and so forth.

[trevordblack]

This belongs in both the README and in the index.html, maybe even in the opening introduction of book 1

[hollasch]

Yeah, I was thinking about the introduction to book 1. That should be sufficient to inform the reader of the underlying philosophy. That said, we should add some lightweight guidance as well in the CONTRIBUTING doc about the intent of the code and our approach to things like engineering quality, performance, utility, and the like. I think that with those two, we don't need to put this up front (or not more than a sentence) in the README or on the web site.

[hollasch]

We also need to be careful not to discourage too much simple improvements to the code that still meet our requirements for simplicity and exposition.

[trevordblack]

Sees stack of issues in v4

so it's one of those "Do as I say, not as I do" kind of deals?

[hollasch]

If you have an issue with one or more of our work items, it would probably be more productive to have those discussions in the associated issues.

[trevordblack]

It was a bad joke

[hollasch]

No, Trevor. It's no parking in the yellow zone. The white zone is for loading and unloading of passengers only.