[logback-dev] [qos-ch/logback] c08834: Add CONTRIBUTING.md

[Tony Trinh]

  Branch: refs/heads/master
  Home:   https://github.com/qos-ch/logback
  Commit: c0883463c9c87c8d0f28e9185d7db819deb23483
      https://github.com/qos-ch/logback/commit/c0883463c9c87c8d0f28e9185d7db819deb23483
  Author: Tony Trinh <tony19 at gmail.com>
  Date:   2014-03-30 (Sun, 30 Mar 2014)

  Changed paths:
    A CONTRIBUTING.md

  Log Message:
  -----------
  Add CONTRIBUTING.md

Added a file to describe general guidelines for submitting pull requests.