create: should not print out 'Not-documented' in the help

[grahamwhaley]

When you ask create_stack.sh for help, it prints out Not-documented for a number of entries... which, is not helpful ;-)

$ ./create_stack.sh -h
Usage: ./create_stack.sh [subcommand]

Subcommands:

        all:            minimal + storage + monitoring + miscellaneous
        cni:            Setup network for running cluster
        help:           show this message
        init:           Only inits a cluster using kubeadm
        metallb:        Not-documented
        minimal:        init + cni +  kata + metrics
        monitoring:     Not-documented
        nfd:            node feature discovery
        npd:            Not-documented
        storage:        Not-documented

That looks to have been added in #93 . I wish we'd actually document what those extra commands are, even if they are documented as 'experimental', 'for test' or 'beta' etc.