RFR: merge-bot: minor improvements to message

[Erik Helin]

Hi all,

please review these refinements to instructions from the merge bot.

Testing:
- `make test` passes on Linux x64

Thanks,
Erik

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Commit messages:
 - merge-bot: minor improvements to message

Changes: https://git.openjdk.java.net/skara/pull/547/files
 Webrev: https://webrevs.openjdk.java.net/skara/547/webrev.00
  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/skara/pull/547.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/547/head:pull/547

PR: https://git.openjdk.java.net/skara/pull/547