Related, and more generally:

    :help object<CTRL-D>
    objects                 text-objects            vimwiki-text-objects
    object-select           sql-object-motions      sql-predefined-objects
    object-motions          text-objects-changed    +textobjects
    :help object

shows all help subjects with "object" in their name.

Then change the help query to whichever subject looks interesting.