Section titles in the Sphinx sidebar

Is there any way to add section titles in the left menu of Sphinx documentation? I know you can do it if you use MkDocs (for example here), but is there a way to do this in Sphinx and ReSTructured text?

I want to divide my documentation into separate sections (e.g. Installation instructions, Running the program, etc.), with the titles of those sections appearing as text in the left menu.

Finally figured out how you can do it in Sphinx...

There is a :caption: directive that allows you to add a caption to the table of contents. For example, the table of contents for readthedocs looks like this:

.. toctree::
   :maxdepth: 2
   :caption: User Documentation # <-- This is what I was looking for

   getting_started
   versions
   [...]

The :caption: User Documentation adds the "User Documentation" section header to the sidebar:

I don't know why there is all that wite-space after the caption, but I guess it's just an issue with the theme...