Hide redundant ToC from docs homepage

Currently the table of contents appears twice on the docs home page
`https://cheroot.cherrypy.dev/en/latest/`: both in the left hand
selection panel and in the main contents next to it. This commit
removes the duplicated content in the main panel.

Author: julianz-

docs/index.rst

@@ -6,21 +6,25 @@ Welcome to Cheroot documentation!
 .. toctree::
    :maxdepth: 1
    :glob:
+   :hidden:
 
    history
 
 .. toctree::
    :caption: Contributing
+   :hidden:
 
    contributing/guidelines
 
 .. toctree::
    :caption: Maintenance
+   :hidden:
 
    contributing/release_guide
 
 .. toctree::
    :caption: Reference
+   :hidden:
 
    devguide
    Private (dev) API autodoc <pkg/modules>