docs: Remove the compat-only features in 'Differences to React'

[rschristian]

As the title suggests, this removes the 'Features exclusive to preact/compat' subsection of the 'Differences to React' page.

This section feels quite misplaced: I think users come to this page to see what switching to Preact and its ecosystem can offer them (and we should flesh this out, signals?), not the specifics of which features sit in core vs compat. If we want to provide commentary on why certain features sit where, I think that's better for API reference or a greatly expounded section here (which I don't have the time/interest for at the moment), as currently we only talk about why Children specifically is unnecessary.

[github-actions]

Size Change: 0 B

Total Size: 449 kB

ℹ️ View Unchanged

Filename	Size
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build/assets/docsearch-********.js	28.9 kB
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build/assets/index-********.js	33.2 kB
build/assets/index-********.css	9.85 kB
build/assets/repl-********.css	1.51 kB
build/assets/repl-********.js	148 kB
build/assets/repl-page-********.js	7.65 kB
build/assets/repl.worker-********.js	213 kB
build/assets/style-********.css	3.07 kB
build/assets/style.module-********.js	159 B
build/assets/tutorial-page-********.js	1.99 kB
build/assets/tutorial-page-********.css	1.76 kB

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