RFR: 8278587: StringTokenizer(String, String, boolean) documentation bug

[Naoto Sato]

This is a doc fix to `StringTokenizer`, where the original spec does not account for the delimiter's length in the case of a supplementary character. Corresponding CSR has been drafted: https://bugs.openjdk.java.net/browse/JDK-8278814

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Commit messages:
 - 8278587: StringTokenizer(String, String, boolean) documentation bug

Changes: https://git.openjdk.java.net/jdk/pull/6836/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6836&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278587
  Stats: 5 lines in 1 file changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6836.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6836/head:pull/6836

PR: https://git.openjdk.java.net/jdk/pull/6836