RFR: 8371815: API docs for 2-arg StructuredTaskScope.open should say timeout may expire before or while waiting in join

[Alan Bateman]

The 2-arg STS.open method currently has "If the timeout expires before the scope has joined", it should say "If the timeout expires before or while waiting in join". The update brings this sentence into line with the same phrase used in other places in the API docs that speak of timeouts.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/28526/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28526&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371815
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/28526.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28526/head:pull/28526

PR: https://git.openjdk.org/jdk/pull/28526