docs: wire up compiler/runtime warnings/errors (#322)

* docs: wire up compiler/runtime warnigns/errors

* allow (and properly style) code blocks in headings

* testbed

* wire up correct branch

* add [!NOTE] type

* sync

* back to main

* lint

* sync

* Revert "add [!NOTE] type"

This reverts commit 3d6ceaa.

* sync

* Revert "allow (and properly style) code blocks in headings"

This reverts commit 1501e5b.

* remove copy-to-clipboard buttons from code blocks without a lang

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Co-authored-by: Rich Harris <rich.harris@vercel.com>