Update required and optional sections in HTML recipe

[ddbeck]

This PR implements the recipe changes discussed in #55.

One area of uncertainty here is the order of the styling with CSS section. This is a newly defined section and I couldn't find an example of one of these in the wild. My ordering is basically a guess.

[wbamberg]

Thanks @ddbeck ! I think we also decided to remove usage_notes and fold it into overview (#55 (comment)).

On order, perhaps it would be best to have all the named sections (except see_also), then all the custom sections?

Like:

related_content: /content/related_content/html.yaml
body:
- prose.short_description
- meta.interactive_example?
- prose.overview
- prose.attributes_text?
- meta.attributes
- prose.styling?
- prose.accessibility_concerns?
- prose.*
- meta.examples
- meta.info_box:
    - meta.api
    - meta.permitted_aria_roles
    - meta.tag_omission
- meta.browser_compatibility
- prose.see_also

...it just seems like a simpler rule that way.

[ddbeck]

Thanks, @wbamberg! Done.

[wbamberg]

Thanks @ddbeck !