RFR: 8272339: Update notes section from serialver man page

[Stuart Marks]

Quick doc-only change. I don't think this needs a CSR, since it contains changes only to the "notes" section, which is non-normative.

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Commit messages:
 - JDK-8272339 Update notes section from serialver man page

Changes: https://git.openjdk.org/jdk/pull/22289/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22289&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8272339
  Stats: 12 lines in 1 file changed: 0 ins; 7 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/22289.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22289/head:pull/22289

PR: https://git.openjdk.org/jdk/pull/22289