RFR: JDK-8324231: bad command-line option in make/Docs.gmk

[Jonathan Gibbons]

Please review an almost trivial change to move the position of an HTML end tag to avoid nested use of the tag.

There is no change to the visual presentation, because the macro `$(DRAFT_MARKER_STR)` itself uses `<strong>` (that was the cause of the nested tags).

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Commit messages:
 - JDK-8324231: bad command-line option in make/Docs.gmk

Changes: https://git.openjdk.org/jdk/pull/17505/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17505&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324231
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17505.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17505/head:pull/17505

PR: https://git.openjdk.org/jdk/pull/17505