RFR: JDK-8223356: Bad placement of marker comment in module-summary.html

[Hannes Wallnöfer]

Please review this simple change to move the marker comment for the start of the module description up one line to make it precede the `<section>` element.

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Commit messages:
 - JDK-8223356: Bad placement of marker comment in module-summary.html

Changes: https://git.openjdk.java.net/jdk/pull/5946/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5946&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8223356
  Stats: 11 lines in 3 files changed: 7 ins; 4 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5946.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5946/head:pull/5946

PR: https://git.openjdk.java.net/jdk/pull/5946