Add support for sections/chapters with linkable HTML IDs

[marcuswhybrow]

YouTube has the concept of chapters for timestamping sections of the video. This is a really useful way to find things.

I immediately thought of markdown headings. Many parsers will automatically add an HTML ID attribute to each title, which allow links to reference that part of the page using an HTTP fragment.

However there are many markdown heading types, from level 1 to 6, I believe. Using markdown headings improves the plain markdown readability.

If the medium is audio or video, a section should always specify a timestamp, and this should be enforced at build time. ID's should be auto generated from the heading text. Something like this, perhaps:

RP: Okay,

## Caffeine and it's effects [1:30]

Well, I ...

However, I don't like that markdown authors are free to specify the sections heading level (1 to 6), which will lead to variation in usage. For example I'd use level 2 headings, represented by ##, but others may like level 1 or level 3 headings.

The Goldmark markdown parser Ray Peat Rodeo uses is very extensible. The easiest option would be to perform a final transform step that inspects all headings and enforces any style guidelines. This step might also catalog the section names, and determine if the heading contains a timestamp, and perhaps panic if timestamps are not defined when they should be.