The way you make the hierarchy of documentation pages is via the command
toctree::.
(toctree:: in the Sphinx docs).
toctree:: refers to other pages by their path relative to the current
document. Multi-level hierarchies (nesting) is done by having toctree::
commands in the documents referred to by this toctree::.
If you want a page to have children pages, but not show them, you can use the
toctree:: command with the option :hidden:.