[GRASS-git] [OSGeo/grass] 84d699: CONTRIBUTING.md: intro added for newcomers (#1566)

[Markus Neteler]

  Branch: refs/heads/releasebranch_7_8
  Home:   https://github.com/OSGeo/grass
  Commit: 84d699c4eb7e42d119b036a7c38eadfd8259cf42
      https://github.com/OSGeo/grass/commit/84d699c4eb7e42d119b036a7c38eadfd8259cf42
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2021-05-08 (Sat, 08 May 2021)

  Changed paths:
    M CONTRIBUTING.md

  Log Message:
  -----------
  CONTRIBUTING.md: intro added for newcomers (#1566)

Related questions on grass-user suggested that there is a documentation gap. This PR attempts to fill it.