RFR: mlbridge: use consistent conf for webrevs

[Erik Helin]

Hi all,

please review this small patch that makes the configuration for the mlbridge bot use consistent spelling for the
"webrevs" fields.

Testing:
- [x] `make test` on Linux x64 passes

Thanks,
Erik

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Commit messages:
 - mlbridge: use consistent conf for webrevs

Changes: https://git.openjdk.java.net/skara/pull/724/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=724&range=00
  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/skara/pull/724.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/724/head:pull/724

PR: https://git.openjdk.java.net/skara/pull/724