[website] removed h3 from outline, fixed some API pages

[sheila-semrush]

Motivation and Context

I removed H3 headings from the outline on API pages because it was redundant in the majority of the cases. H3 headings almost always duplicate parent headings:

Also fixed some specific API pages: fixed structure, added missing types.

We could get rid of manually added H2 headings and replace auto generated type name headings with H2 level, but there are some concerns:

1. There's often content before the H3 heading (some short text about the component). If we want to get rid of manual H2 headings, we need to design a way to feed this content into the TypesView VitePress component.
2. Type names are often harder to read or not very descriptive (InputTags.Value vs InputTagsValueProps). I'm also not sure it's beneficial for anyone to know the type names.
3. There are pages where there are deprecated types, and it's better to group/label them. Example: DropdownMenu.
4. There are 1-2 pages where there's too many types, and it's better to group them. Main case is d3 chart.

In conclusion, I think it would be easier to stay with only the manually edited H2 headings in the outline for now.

I have some ideas how we could improve API pages structure, but it would require more work, so it's better to do it in a separate task.

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Nice improve.

Checklist:

• I have updated the documentation accordingly.
• I have added new tests on added of fixed functionality.