feat(docs): planetar component descriptions & rethink naming [1h]

### Prerequisite

#19

### Goal

- [ ] write a short component description for each component in a JSDoc above the `export default` section

- [ ] rename `ApiComponentExample` to `ApiCardInteractive`

- [ ] rename`MarkdownSection` and `CodeBlockSection` to something else:

So we have some components which end in `...Section` because they are to be used as a documentation "section", which incorporate whatever `...` stands for with an extra section of some text?

This makes sense.

However, `MarkdownSection` and `CodeBlockSection` are a bit different as they just allow the use of a `filePath` as opposed to `Markdown` and `CodeBlock`.
Things to think about:

> is it really necessary to separate `Markdown` and `CodeBlock` with their counterparts that can accept a filePath?

I believe so because projects not relying on webpack that still want to use `Markdown` might have problems when the webpack related code is included. But we need to rename `Section` to something else.

Review prerequisite #19 and inspect the component exports, especially the areas above each export default. Identify every component needing a short JSDoc description, then resolve the requested renames and verify that the final names consistently reflect the distinction between Markdown/CodeBlock and their filePath-based variants.

Written by the indexing model from the issue text.