RFR: 8312104: Update java man pages to include new security category in -XshowSettings

[Sean Coffey]

Incorporate man page changes related to JDK-8281658 and related issues (including JDK-8311653)

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Commit messages:
 - minor tidy up
 - bullet points
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/19078/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19078&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312104
  Stats: 17 lines in 1 file changed: 15 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19078.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19078/head:pull/19078

PR: https://git.openjdk.org/jdk/pull/19078