In order to add a group to your help string, use the following form:
(group ([OPTIONS…]) ITEMS…)
OPTIONS are key/value pairs. ITEMS simply are arbitrary text, option or sub-group descriptions as we’ve just seen.
The following OPTIONS are currently available.
:header ¶A string which will be displayed above the group’s contents in the help string. The same formatting recommendations as for arbitrary text apply (see Text).
:hidden ¶When non-nil, the group won’t appear in the help string. Hidden
groups can still be displayed individually though (see Help). For
instance, the Clon built-in group is hidden in the regular help
string, but the --clon-help option still displays it individually.