RFR: 8366375: Collator example for SECONDARY uses wrong code point

[Naoto Sato]

Minor documentation corrections in Collator

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/27007/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27007&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366375
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/27007.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27007/head:pull/27007

PR: https://git.openjdk.org/jdk/pull/27007