Add documentation

Author: rnc

README.md

@@ -6,3 +6,13 @@ At present this consists of two images:
 
  * jbs-ubi7-builder
  * jbs-ubi8-builder
+
+## Updating Images
+
+In order to update the Dockerfiles in jbs-ubi7-builder / jbs-ubi8-builder do *not* update them directly but modify the `Dockerfile.template` and then run `generate.sh`.
+
+To update versions (e.g. for Maven/Gradle/Ant) add or modify the versions in `image-config.yaml` and then add the appropriate version/SHA256 to `generate.sh`. For Ant, the versions are also referenced with the main jvm-build-service repository.
+
+Once the image has been successfully updated and the PR merged then this should then be updated in the main jvm-build-service repository by modifying:
+* deploy/operator/config/kustomization.yaml
+* deploy/operator/config/system-config.yaml

image-config.yaml

@@ -3,9 +3,6 @@ kind: SystemConfig
 metadata:
   name: cluster
 spec:
-  #This is used to drive the builder image build
-  #Versions places here for gradle will be used generate the relevant dockerfiles
-  #after you run generate.sh
   builders:
     ubi7:
       tag: jdk:7,maven:3.8.8;3.9.5,ant:1.9.16