RFR: 8351555: Help section added in JDK-8350638 uses invalid HTML

[Hannes Wallnöfer]

Please review a change to fix the HTML for the new Keyboard Navigation section added in [JDK-8350638](https://bugs.openjdk.org/browse/JDK-8350638). Instead of adding the `<ul>` element to the `<p>` element, both elements are added to the `<section>` element.

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Commit messages:
 - 8351555: Help section added in JDK-8350638 uses invalid HTML

Changes: https://git.openjdk.org/jdk/pull/23969/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23969&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351555
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23969.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23969/head:pull/23969

PR: https://git.openjdk.org/jdk/pull/23969