docs: document the _private methods
This is a reference documentation, so it makes sense for it to be
reasonably complete.
@@ -173,4 +173,4 @@ texinfo_documents = [
'Miscellaneous'),
]
-autodoc_default_flags = ['members', 'undoc-members', 'show-inheritance']
+autodoc_default_flags = ['members', 'undoc-members', 'private-members', 'show-inheritance']
