Usage: 

    ./docker_reg_tool REGISTRY_BASE_URL ACTION [OPTIONS..]
    
    Actions:

    - list               list repos

    - list REPO          list tags for repo

    - delete REPO TAG    delete tag for repo

    Example:

    List all repos
        /$ ./docker_reg_tool https://registry.my.domain list

    List tags for one repo
        /$ ./docker_reg_tool https://registry.my.domain list some-repo

    Delete tag for a repo
        /$ ./docker_reg_tool https://registry.my.domain delete some-repo some-tag