RFR: 8345324: Update comment in SourceVersion for language evolution history for changes in 24

[Joe Darcy]

Update source-level, in other words non-javadoc, comment to describe the actual language changes made in 24.

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Commit messages:
 - JDK-8345324: Update comment in SourceVersion for language evolution history for changes in 24

Changes: https://git.openjdk.org/jdk/pull/22495/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22495&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345324
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22495.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22495/head:pull/22495

PR: https://git.openjdk.org/jdk/pull/22495