merge with stable

doc/extensions.rst

@@ -3,34 +3,12 @@
 Sphinx Extensions
 =================
 
-.. module:: sphinx.application
-   :synopsis: Application class and extensibility interface.
-
-Since many projects will need special features in their documentation, Sphinx is
-designed to be extensible on several levels.
-
-This is what you can do in an extension: First, you can add new
-:term:`builder`\s to support new output formats or actions on the parsed
-documents.  Then, it is possible to register custom reStructuredText roles and
-directives, extending the markup.  And finally, there are so-called "hook
-points" at strategic places throughout the build process, where an extension can
-register a hook and run specialized code.
-
-An extension is simply a Python module.  When an extension is loaded, Sphinx
-imports this module and executes its ``setup()`` function, which in turn
-notifies Sphinx of everything the extension offers -- see the extension tutorial
-for examples.
-
-The configuration file itself can be treated as an extension if it contains a
-``setup()`` function.  All other extensions to load must be listed in the
-:confval:`extensions` configuration value.
-
-.. toctree::
-
-   ext/tutorial
-   ext/appapi
-   ext/builderapi
+Since many projects will need special features in their documentation, Sphinx
+allows to add "extensions" to the build process, each of which can modify almost
+any aspect of document processing.
 
+This chapter describes the extensions bundled with Sphinx.  For the API
+documentation on writing your own extension, see :ref:`dev-extensions`.
 
 Builtin Sphinx extensions
 -------------------------