Integrated: 7902887: JTHarness HTML documentation requires minor improvements

[Dmitry Bessonov]

HTML checkers report some minor issues with JTH docs that need to be fixed

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Commit messages:
 - 7902887: JTHarness HTML documentation requires minor improvements

Changes: https://git.openjdk.java.net/jtharness/pull/9/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jtharness&pr=9&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7902887
  Stats: 421 lines in 22 files changed: 90 ins; 31 del; 300 mod
  Patch: https://git.openjdk.java.net/jtharness/pull/9.diff
  Fetch: git fetch https://git.openjdk.java.net/jtharness pull/9/head:pull/9

PR: https://git.openjdk.java.net/jtharness/pull/9