Simplify example but add clarity. (#1144)

Some people might add the example code to the top of the file, in which case `alabaster` will overwrite later. Also, localization is important but not so important for people using this for the first time. My concern is that many people end up with Alabaster on RTD deployments after Sphinx 4 made it the default.

Co-authored-by: Aaron Carlisle <carlisle.b3d@gmail.com>

README.rst

@@ -33,21 +33,15 @@ This theme is distributed on PyPI_ and can be installed with ``pip``:
 
    $ pip install sphinx-rtd-theme
 
-To use the theme in your Sphinx project, you will need to add the following to
-your ``conf.py`` file:
+To use the theme in your Sphinx project, you will need to edit
+your ``conf.py`` file's ``html_theme`` setting:
 
 .. code:: python
 
-    import sphinx_rtd_theme
-
-    extensions = [
-        ...
-        "sphinx_rtd_theme",
-    ]
-
     html_theme = "sphinx_rtd_theme"
 
-For more information read the full documentation on `installing the theme`_
+For more information, including a full example with localized strings enabled,
+read the documentation on `installing the theme`_.
 
 .. _PyPI: https://pypi.python.org/pypi/sphinx_rtd_theme
 .. _installing the theme: https://sphinx-rtd-theme.readthedocs.io/en/latest/installing.html