RFR: 8336679: Add @implSpec for the default implementations in Process.waitFor() [v3]

[Brian Burkhalter]

On Tue, 23 Jul 2024 20:58:01 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> This is a simple doc-only change that follows up [JDK-8336479](https://bugs.openjdk.org/browse/JDK-8336479). A corresponding CSR has also been drafted.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   apiNote -> implNote

Re-reviewed.

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Marked as reviewed by bpb (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20285#pullrequestreview-2197094696