[GRASS-git] [OSGeo/grass] 77121d: contributing: Improve where doc is located (#2535)

[Vaclav Petras]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 77121d941c48d11794fb1d3b56d1d637842afe57
      https://github.com/OSGeo/grass/commit/77121d941c48d11794fb1d3b56d1d637842afe57
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2022-08-28 (Sun, 28 Aug 2022)

  Changed paths:
    M CONTRIBUTING.md
    M README.md

  Log Message:
  -----------
  contributing: Improve where doc is located (#2535)

* Move C API doc compilation from readme.
* Move compilation intro to the end of contributing file.
* Add subsection about testing.
* Move intro to an about section.
* Emphasize source code contributions in the contributing file in the repo.

Co-authored-by: Veronica Andreo <veroandreo at gmail.com>