[logback-dev] [qos-ch/logback] f4a750: Update CONTRIBUTING.md

[Tony Trinh]

  Branch: refs/heads/master
  Home:   https://github.com/qos-ch/logback
  Commit: f4a75098744bfbd1a3da3f730067b7fa9309abb9
      https://github.com/qos-ch/logback/commit/f4a75098744bfbd1a3da3f730067b7fa9309abb9
  Author: Tony Trinh <tony19 at gmail.com>
  Date:   2014-12-28 (Sun, 28 Dec 2014)

  Changed paths:
    M CONTRIBUTING.md

  Log Message:
  -----------
  Update CONTRIBUTING.md