Headings as anchor links?

[aminomancer]

On our new messaging-system docs page, we've added all the data that used to be here on firefox-source-docs.

Generally it works great, but there are a couple things that make the doc less useful than the original was. I can't show this on the original page since it's been removed, but see this page for example.

So the firefox-source-docs page has syntax highlighting for code blocks and a paragraph icon next to each heading that allows one to link to that specific section. The page is so long that it's hard to link to a specific item in the doc without it. Typing in an anchor link manually like #spotlight-pings doesn't work either.