Allow modification of additional help texts
Hammer allows to append additional texts to standard help generated for commands. It's currently not possible to modify the help text and pugins can't add paragraphs or lists to existing sections in help.
TextBuilder in help should provide interface for looking up help items (sections, lists, texts) and modifying their contents, e.g.:
# Find existing section ':provider_options' and add section 'Libvirt' base.extend_help do |h| h.find_section(:provider_options).section(_('Libvirt')) do |h| h.list([ ['cpus', _('Number of CPUs')], ['memory', _('String, amount of memory, value in bytes')], ['start', _('Boolean (expressed as 0 or 1), whether to start the machine or not')] ]) end end