RFR: 8284387: Fix formatting of doc comments in jdk.javadoc

[Pavel Rappo]

JDK-8284362 highlighted some issues with formatting of top-level doc comments. This PR fixes those issues and similar issues elsewhere in jdk.javadoc.

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Commit messages:
 - Update copyright years
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/8126/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8126&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284387
  Stats: 174 lines in 62 files changed: 2 ins; 41 del; 131 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8126.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8126/head:pull/8126

PR: https://git.openjdk.java.net/jdk/pull/8126