[jdk26] RFR: 8375683: Add notes for sctp tests

[Iris Clark]

On Sun, 25 Jan 2026 01:15:18 GMT, SendaoYan <syan at openjdk.org> wrote:

> Hi all,
> 
> This pull request contains a backport of commit [93255602](https://github.com/openjdk/jdk/commit/932556026d6d49fe6f74d4ec4afcb72448611766) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository to jdk26 branch.
> 
> The commit being backported is add the descriptions about hwo to running the SCTP tests. Only touch the testing.md/testing/html.
> 
> Thanks!

Confirmed backport matches changes already pushed to 'master' branch.

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Marked as reviewed by iris (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29399#pullrequestreview-3707063527