memoir: pt. 3 section headers

memoir: pt. 3 section headers

If both Said (private correspondence) and Ray
(https://www.greaterwrong.com/posts/ZjXtjRQaD2b4PAser/a-hill-of-validity-in-defense-of-meaning/comment/Lmhum2tXLXzmbKvm5)
agree that I need section headers, then I probably need section
headers.

I was feeling reluctant about it, but after doing it, I agree that
this is a lot better.

I have mixed feelings about giving the "Why are you a boy?" anecdote
the prominence of its own section. (I wanted it to be subtle
foreshadowing, but if it gets its own section, then it's blantant
foreshadowing, which I choose to lampshade with a Suspiciously
Specific Denial.)

I'm not sure where the defaults were inherited from, but <h2> was too
big and <h3> was too small, so I edit the CSS to make <h3> bigger.

(Ideally, the titles would be anchor links ... do I need to write a
Pelican patch or plugin for that?)