Restore matplotlib.__doc__ in Sphinx docs

Since we already have an explicit listing of module members, that needs
to be turned off here. Also, don't add it to the index as we already
have `matplotlib` pointing to the top level page (though maybe that
should change?)

Fixes matplotlib#17973

Author: QuLogic

doc/api/matplotlib_configuration_api.rst

@@ -4,6 +4,11 @@
 
 .. py:currentmodule:: matplotlib
 
+.. automodule:: matplotlib
+   :no-members:
+   :no-undoc-members:
+   :noindex:
+
 Backend management
 ==================
 

lib/matplotlib/__init__.py

@@ -63,7 +63,7 @@
     :mod:`matplotlib.ticker`
         Calculation of tick mark locations and formatting of tick labels.
 
-    :mod:`matplotlib.backends`
+    :doc:`matplotlib.backends </api/index_backend_api>`
         A subpackage with modules for various GUI libraries and output formats.
 
 The base matplotlib namespace includes:
@@ -81,7 +81,7 @@
 developed and maintained by a host of others.
 
 Occasionally the internal documentation (python docstrings) will refer
-to MATLAB&reg;, a registered trademark of The MathWorks, Inc.
+to MATLAB®, a registered trademark of The MathWorks, Inc.
 
 """