RFR: 8320788: The system properties page is missing some properties

[Naoto Sato]

Adding an explanation of the locale-related system properties in the `System.getProperties()` method. Corresponding CSR has alos been drafted.

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Depends on: https://git.openjdk.org/jdk/pull/17065

Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/17317/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17317&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320788
  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17317.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17317/head:pull/17317

PR: https://git.openjdk.org/jdk/pull/17317