doc: Add "setuptools" to usage guide

Signed-off-by: Stephen Finucane <stephen@that.guru>

doc/contents.rst

@@ -15,11 +15,11 @@ Sphinx documentation contents
    usage/builders/index
    usage/extensions/index
    usage/advanced/intl
+   usage/advanced/setuptools
 
    intro
    man/index
    theming
-   setuptools
    templating
    latex
    extdev/index

doc/usage/quickstart.rst

@@ -321,7 +321,7 @@ More topics to be covered
 - :doc:`Other extensions </usage/extensions/index>`:
 - Static files
 - :doc:`Selecting a theme </theming>`
-- :doc:`/setuptools`
+- :doc:`/usage/advanced/setuptools`
 - :ref:`Templating <templating>`
 - Using extensions
 - :ref:`Writing extensions <dev-extensions>`