RFR: 8259816: Typo in java.util.stream package description

[Stuart Marks]

Fix a typo, and change an example to use Stream.toList().

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Commit messages:
 - 8259816: Typo in java.util.stream package description

Changes: https://git.openjdk.java.net/jdk/pull/2249/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2249&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259816
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2249.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2249/head:pull/2249

PR: https://git.openjdk.java.net/jdk/pull/2249