RFR: Use proper markdown formatting in help message

[Robin Westberg]

Hi all,

Please review this trivial fix in the help message given when a pull request does not contain a required reference to an issue.

Best regards,
Robin

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Commits:
 - 6b5a06f4: Use proper markdown formatting

Changes: https://git.openjdk.java.net/skara/pull/193/files
 Webrev: https://webrevs.openjdk.java.net/skara/193/webrev.00
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/193.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/193/head:pull/193

PR: https://git.openjdk.java.net/skara/pull/193