[phobos] [dlang/phobos] 95e0c6: Readd contributing.md hint

[GitHub via phobos]

  Branch: refs/heads/walter_andrei_action_list
  Home:   https://github.com/dlang/phobos
  Commit: 95e0c646c179b5b8b2119cd96186d70442fd6937
      https://github.com/dlang/phobos/commit/95e0c646c179b5b8b2119cd96186d70442fd6937
  Author: Robert Schadek <robert.schadek at informatik.uni-oldenburg.de>
  Date:   2016-06-19 (Sun, 19 Jun 2016)

  Changed paths:
    M README.md

  Log Message:
  -----------
  Readd contributing.md hint