docs(ct-base): clarify support image tags IQSS#8932

Adding notes about the image tags produced by the community
for reuse in the community. Document final tagging
strategy, using the branch name (develop/main) instead of
the Java version or sth.

Reshape the automated builds and publishing part to be included
in the supported tags and build instructions section to reduce
text complexity and group matching parts together.

doc/sphinx-guides/source/container/base-image.rst

@@ -12,6 +12,17 @@ IQSS will not offer you support how to deploy or run it, please reach out to the
 You might be interested in taking a look at :doc:`../developers/containers`, linking you to some (community-based)
 efforts.
 
+Supported Image Tags
+++++++++++++++++++++
+
+This image is sourced within the main upstream code repository of the Dataverse software. Development and maintenance
+happens there (again, by the community). Community supported image tags are based on the two most important branches:
+
+- ``develop`` representing the unstable state of affairs in Dataverse's development branch
+  (`Dockerfile <https://github.com/IQSS/dataverse/tree/develop/modules/container-base/src/main/docker/Dockerfile>`__)
+- ``release`` representing the latest stable release in Dataverse's main branch
+  (`Dockerfile <https://github.com/IQSS/dataverse/tree/master/modules/container-base/src/main/docker/Dockerfile>`__)
+
 
 
 Image Contents
@@ -51,8 +62,12 @@ Or move to the module and execute:
 
 Some additional notes, using Maven parameters to change the build and use ...:
 
+- | ... a different tag only: add ``-Dbase.image.tag=tag``.
+  | *Note:* default is ``develop``
 - | ... a different image name and tag: add ``-Dbase.image=name:tag``.
-  | *Note:* default is ``gdcc/base:${target.java.version}-jre``
+  | *Note:* default is ``gdcc/base:${base.image.tag}``
+- ... a different image registry than *Docker Hub*: add ``-Ddocker.registry=registry.example.org`` (see also
+  `DMP docs on registries <https://dmp.fabric8.io/#registry>`__)
 - ... a different Payara version: add ``-Dpayara.version=V.YYYY.R``.
 - | ... a different Temurin JRE version ``A``: add ``-Dtarget.java.version=A`` (i.e. ``11``, ``17``, ...).
   | *Note:* must resolve to an available Docker tag ``A-jre`` of Eclipse Temurin!
@@ -61,6 +76,17 @@ Some additional notes, using Maven parameters to change the build and use ...:
   image available from local or remote (e. g. Docker Hub).
 - ... a different UID/GID for the ``payara`` user/group: add ``-Dbase.image.uid=1234`` (or ``.gid``)
 
+Automated Builds & Publishing
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+To make reusing most simple, the image is built with a Github Action within the IQSS repository and then pushed
+to `Docker Hub gdcc/base repository <https://hub.docker.com/r/gdcc/base>`_. It is built and pushed on every edit to
+its sources plus uncached scheduled nightly builds to make sure security updates are finding their way in.
+
+*Note:* For the Github Action to be able to push to Docker Hub, two repository secrets
+(DOCKERHUB_USERNAME, DOCKERHUB_TOKEN) have been added by IQSS admins to their repository.
+
+
 
 Tunables
 ++++++++
@@ -234,18 +260,6 @@ The HTTPS listener (on port 8181) becomes deactivated during the build, as we wi
 application server and handle SSL/TLS termination at this point. Save the memory and some CPU cycles!
 
 
-Publishing and Updates
-++++++++++++++++++++++
-
-This image is sourced within the main upstream code repository of the Dataverse software. Development and maintenance
-happens there (again, by the community).
-
-To make reusing most simple, the image is built with a Github Action within the IQSS repository and then pushed
-to `Docker Hub gdcc/base repository <https://hub.docker.com/r/gdcc/base>`_. It is built and pushed on every edit to
-its sources plus uncached scheduled nightly builds to make sure security updates are finding their way in.
-
-Note: for the Github Action to be able to push to Docker Hub, two repository secrets
-(DOCKERHUB_USERNAME, DOCKERHUB_TOKEN) have been added by IQSS admins to their repository.
 
 .. _base-entrypoint: