As an example, compare https://pip.pypa.io/en/latest/reference/pip_install/ and https://pip.pypa.io/en/stable/reference/pip_install/
The sidebar for stable shows the subsections Usage, Description, Options and Examples, and Description is expandable another level. And there's a full multi-level table of contents at the top of the page. Both of these features are missing from the new layout, which is a significant regression in navigability.