[GRASS-git] [OSGeo/grass] cc51b0: docker: Update dockerhub organization (#3001)

[Carmen Tawalika]

  Branch: refs/heads/releasebranch_8_2
  Home:   https://github.com/OSGeo/grass
  Commit: cc51b087fcaad1b68187f7dd81dc76b48ddb0420
      https://github.com/OSGeo/grass/commit/cc51b087fcaad1b68187f7dd81dc76b48ddb0420
  Author: Carmen Tawalika <mmacata at users.noreply.github.com>
  Date:   2023-06-06 (Tue, 06 Jun 2023)

  Changed paths:
    M .github/workflows/docker.yml
    M docker/README.md

  Log Message:
  -----------
  docker: Update dockerhub organization (#3001)

* update dockerhub organization
* update docs
* Update docker/README.md
* no alpine docker build for g78 anymore

Co-authored-by: Markus Neteler <neteler at osgeo.org>