Add `tj/n` style version help in `snm --help`

[numToStr]

Example:

Versions:

  Numeric version numbers can be complete or incomplete, with an optional leading 'v'.
  Versions can also be specified by label, or codename,
  and other downloadable releases by <remote-folder>/<version>

    4.9.1, 8, v6.1    Numeric versions
    lts               Newest Long Term Support official release
    latest, current   Newest official release
    auto              Read version from file: .n-node-version, .node-version, .nvmrc, or package.json
    engine            Read version from package.json
    boron, carbon     Codenames for release streams
    lts_latest        node support aliases

    and nightly, rc/10 et al