[GRASS-git] [OSGeo/grass] 444679: Reference CONTRIBUTING.md file in README (#283)

[Vaclav Petras]

  Branch: refs/heads/releasebranch_7_8
  Home:   https://github.com/OSGeo/grass
  Commit: 444679415b31b1b44b137396b3a4b230896eeb22
      https://github.com/OSGeo/grass/commit/444679415b31b1b44b137396b3a4b230896eeb22
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2020-01-16 (Thu, 16 Jan 2020)

  Changed paths:
    M README.md

  Log Message:
  -----------
  Reference CONTRIBUTING.md file in README (#283)