docs: clarify why dokku report information is useful
docs: clarify why dokku report information is useful

Also note that it can be run without any arguments.

Refs #3192
alexquick/dokku,progrium/dokku,claytonbrown/dokku,jimjag/dokku,alexquick/dokku,alexquick/dokku,progrium/dokku,dokku/dokku,dokku/dokku,dokku/dokku,dokku/dokku,dokku/dokku,claytonbrown/dokku,progrium/dokku,progrium/dokku,jimjag/dokku,dokku/dokku,alexquick/dokku,claytonbrown/dokku,alexquick/dokku,alexquick/dokku,progrium/dokku,progrium/dokku,claytonbrown/dokku,alexquick/dokku,dokku/dokku,jimjag/dokku,progrium/dokku,jimjag/dokku,jimjag/dokku,claytonbrown/dokku,claytonbrown/dokku,dokku/dokku,jimjag/dokku,claytonbrown/dokku,jimjag/dokku,alexquick/dokku,progrium/dokku,jimjag/dokku,claytonbrown/dokku