[Integrated] RFR: Use proper markdown formatting in help message

[Robin Westberg]

Changeset: 9f350037
Author:    Robin Westberg <rwestberg at openjdk.org>
Date:      2019-10-09 10:41:11 +0000
URL:       https://git.openjdk.java.net/skara/commit/9f350037

Use proper markdown formatting in help message

Reviewed-by: ehelin

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestCheckIssueVisitor.java