[zanata/zanata-client] e3a8bc: docs: add CONTRIBUTING.md

[GitHub]

  Branch: refs/heads/contributing
  Home:   https://github.com/zanata/zanata-client
  Commit: e3a8bc70776380ca85f884a1cb127144c0cc8b09
      https://github.com/zanata/zanata-client/commit/e3a8bc70776380ca85f884a1cb127144c0cc8b09
  Author: Ding-Yi Chen <dingyichen at gmail.com>
  Date:   2016-03-11 (Fri, 11 Mar 2016)

  Changed paths:
    A CONTRIBUTING.md

  Log Message:
  -----------
  docs: add CONTRIBUTING.md