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

[Brian Burkhalter]

On Mon, 22 Jul 2024 22:10:07 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.

Marked as reviewed by bpb (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20285#pullrequestreview-2192656420