RFR: 2572: Bot help command can include a link to wiki page

[Zhao Song]

Add wiki page link to help command reply

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Commit messages:
 - SKARA-2572

Changes: https://git.openjdk.org/skara/pull/1742/files
  Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1742&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-2572
  Stats: 7 lines in 2 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/skara/pull/1742.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1742/head:pull/1742

PR: https://git.openjdk.org/skara/pull/1742