Render full TOC for release notes

[ajwild]

Part of splitting up #1156.

Before:

After:

The skills will remove the emojis from titles so it'll look a bit cleaner in the future. You could test with #1162.

[dfreier]

Let's try it

[ajwild]

If making the sidebar sections collapsible is important then I'll take another look in a week or two. At the moment it's quicker to scan what's in the release than it used to be, but it might be slower if you wanted to look for a specific feature (one more click but less to read/scroll).

[eileenoo]

I'm not sure about this one. As you said it adds more detail but at the same time it makes it harder to find/jump to a section.
I would do this together with collapsable under menus, in one take.