[zanata/zanata-api] b71d4c: docs: add CONTRIBUTING.md

[GitHub]

  Branch: refs/heads/release
  Home:   https://github.com/zanata/zanata-api
  Commit: b71d4c2fcc34e2b4b9b8198aa76978a315cf2073
      https://github.com/zanata/zanata-api/commit/b71d4c2fcc34e2b4b9b8198aa76978a315cf2073
  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