I have found some unofficial documentation for doing an offline dump of the database in a container here. It'd be nice if we had some full-fledged "official" docs about this.
Please also consider cross-referencing (i.e., just add links) these documentations with the "main" instructions for using these commands. (E.g., here for dump/load, here for import tool.)
Granted that this could be considered more of a Docker how-to and thus does not belong in a Neo4J manual, but it would still be extremely helpful if we had official guidance and recommendation for doing these types of operations when running in a container.