docker: update GRASS GIS 7 docker matrix

docker/README.md

@@ -1,18 +1,15 @@
 [![Docker Pulls](https://img.shields.io/docker/pulls/mundialis/grass-py3-pdal.svg)](https://grass.osgeo.org/download/software/docker-images/)
 
-# GRASS GIS docker matrix
+# GRASS GIS 7 docker matrix
 
 | Base image   | Docker tag      | GRASS GIS  | PROJ  | GDAL  | PDAL  | Python | Image size |
 |--------------|-----------------|------------|-------|-------|-------|--------|------------|
-| Ubuntu 20.04 | latest-ubuntu   | 7.9.dev    | 6.3.1 | 3.0.4 | 2.2.0 | 3.8.5  | 1.04 GB    |
-| Debian 10.1  | latest-debian   | 7.9.dev    | 5.2.0 | 2.4.0 | 1.8.0 | 3.7.3  | 1.14 GB    |
-| Alpine 3.12  | latest-alpine   | 7.9.dev    | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
-|--------------|-----------------|------------|-------|-------|-------|--------|------------|
-| Ubuntu 20.04 | stable-ubuntu   | 7.8 branch | 6.3.1 | 3.0.4 | 2.2.0 | 3.8.5  | 1.04 GB    |
-| Debian 10.1  | stable-debian   | 7.8 branch | 5.2.0 | 2.4.0 | 1.8.0 | 3.7.3  | 1.14 GB    |
-| Alpine 3.12  | stable-alpine   | 7.8 branch | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
+| Ubuntu 20.04 | latest-ubuntu   | 7.8.x      | 6.3.1 | 3.0.4 | 2.2.0 | 3.8.10 | 1.20 GB    |
+| Debian 10.1  | latest-debian   | 7.8.x      | 5.2.0 | 2.4.0 | 1.8.0 | 3.7.3  | 1.16 GB    |
+| Alpine 3.12  | latest-alpine   | 7.8.x      | 7.0.1 | 3.1.4 | 2.1.0 | 3.8.10 |  185 MB    |
+
 
-Last update: 16 Dec 2020 (source: https://hub.docker.com/r/mundialis/grass-py3-pdal/builds)
+Last update: 16 Mar 2022 (source: https://github.com/OSGeo/grass/actions/workflows/docker.yml and https://hub.docker.com/r/mundialis/grass-py3-pdal/tags)
 
 # Requirements