Generate a static back-of-a-book style index?

[Skip Montanaro]

I just generated a static website which is nothing more than around
ten years of email messages from a defunct vintage bike mailing list
(170k messages, one per file). Though I've submitted the front page
URL to both Google and Bing, I was thinking that it would be handy to
have something like a static index such as you might find in the back
of a book. I poked around a bit, but the prevalence of JS-based static
websites is hampering the search. I found this on PyPI:

https://pypi.org/project/static_site_index/

but it looks fairly unmaintained and contains no documentation.
(Fortunately, it appears small, so I will at least skim the code to
see if it looks useful.)

Surely this is a solved problem, hopefully in Python?

Thx,

Skip