RFR: 8346667: Doccheck: warning about missing </span> before <h2> [v2]

[Nizar Benalla]

> Please review this doc-only patch to avoid some unwanted failures in our HTML checks. 
> 
> Javadoc wraps everything under `@param` in a `<span>`, so having an `h2` tag there trips some of our tests that use html validators (html-tidy and some other tests). I believe you shouldn't have an `<h2>` inside of a span.
> 
> This patch moves the text about "Value-based classes and identity operations" above the `@param` tag, it will now be rendered at the bottom of the class documentation.
> 
> This will need to be backported to JDK 24.
> 
> TIA.

Nizar Benalla has updated the pull request incrementally with two additional commits since the last revision:

 - Move value-based classes description above param tag
 - Revert "replace use of h2 with inline css, trying to get almost the same look"
   
   This reverts commit c86a3e5320eb542d481dfa28fd90d0eaa1f76c29.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22833/files
  - new: https://git.openjdk.org/jdk/pull/22833/files/c86a3e53..bbd753f7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22833&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22833&range=00-01

  Stats: 6 lines in 1 file changed: 3 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22833.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22833/head:pull/22833

PR: https://git.openjdk.org/jdk/pull/22833