RFR: JDK-8262430: doclint warnings in java.base module

[Jonathan Gibbons]

Please review some simple doc fixes in the `java.base` module.  Two were reported by doclint; the spelling error was detected by the IDE.

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Commit messages:
 - JDK-8262430: doclint warnings in java.base module

Changes: https://git.openjdk.java.net/jdk/pull/2734/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2734&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262430
  Stats: 3 lines in 2 files changed: 1 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2734.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2734/head:pull/2734

PR: https://git.openjdk.java.net/jdk/pull/2734