RFR: 8356420: Provide examples on wrapping System.in [v4]

[Chen Liang]

On Mon, 12 May 2025 21:59:29 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> With the introduction of `stdin.encoding` ([JDK-8350703](https://bugs.openjdk.org/browse/JDK-8350703)), some guidance for users to decode `System.in` would be desirable. Adding examples in the field description would help.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reflects more comments

Marked as reviewed by liach (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25155#pullrequestreview-2834978752