Minor Description
Currently the procedure to run the Oracle Integration Suite is based on building the Oracle RDBMS image from the Dockerfiles provided by Oracle.
Recently Oracle has started providing database images, see https://container-registry.oracle.com
Moreover an Oracle employee is maintaining Oracle XE images that are streamlined for testing at https://hub.docker.com/r/gvenzl/oracle-xe and https://github.com/gvenzl/oci-oracle-xe This solves the issue that official images are quite large and make testing resource-intensive and slow.
This proposes to document the available options and to introduce a default value for ORACLE_DOCKER_IMAGE
