[jdk18] RFR: 8278607: Misc issues in foreign API javadoc

[Maurizio Cimadamore]

This patch fixes a number of issues and typos in the foreign API javadoc following another internal round of reviews.

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Commit messages:
 - Misc foreign API javadoc fixes

Changes: https://git.openjdk.java.net/jdk18/pull/17/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=17&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278607
  Stats: 35 lines in 7 files changed: 3 ins; 1 del; 31 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/17.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/17/head:pull/17

PR: https://git.openjdk.java.net/jdk18/pull/17