Autogenerate id attributes from dt elements?

[wbamberg]

This came out of mdn/content#10730, and it had occurred to me before. It used to be possible to add id attributes to random bits of markup so we could link to them, and that's no longer possible in Markdown. In fact one of the main areas this is annoying is in <dl> elements, which we use pretty extensively in MDN. For instance, it would be nice to be able to link to the values of CSS properties.

So I wondered if we might generate id attributes for <dt> elements in the Markdown-to-HTML step, ad we currently do for headings.