[jdk17] RFR: 8269513: Clarify the spec wrt `useOldISOCodes` system property [v4]

[Iris Clark]

On Mon, 28 Jun 2021 20:33:29 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> Please review this small doc change to the system property. Accompanying CSR has also been created.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Missed one.

Marked as reviewed by iris (Reviewer).

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PR: https://git.openjdk.java.net/jdk17/pull/163