[jdk21u-dev] RFR: 8331077: nroff man page update for jar tool

[Martin Doerr]

Clean backport of [JDK-8331077](https://bugs.openjdk.org/browse/JDK-8331077).

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

Commit messages:
 - Backport c21672d8c94da6aa613174744ceaa945ca2a474a

Changes: https://git.openjdk.org/jdk21u-dev/pull/643/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=643&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331077
  Stats: 8 lines in 1 file changed: 4 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/643.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/643/head:pull/643

PR: https://git.openjdk.org/jdk21u-dev/pull/643