Add link to Sphinx docs

Closes #1222

docs/installing.rst

@@ -10,15 +10,10 @@ Install the ``sphinx_rtd_theme`` package (or add it to your ``requirements.txt``
 
     $ pip install sphinx_rtd_theme
 
-In your Sphinx project's ``conf.py`` file, add ``sphinx_rtd_theme`` to the list of enabled extensions and as the active theme:
+In your Sphinx project's ``conf.py`` file, define ``html_theme`` to activate the theme:
 
 .. code:: python
 
-    extensions = [
-        ...
-        'sphinx_rtd_theme',
-    ]
-
     html_theme = "sphinx_rtd_theme"
 
 .. seealso::
@@ -29,19 +24,6 @@ In your Sphinx project's ``conf.py`` file, add ``sphinx_rtd_theme`` to the list
         Officially Supported versions of Python, Sphinx, and other dependencies.
 
 
-.. note::
-
-   Adding this theme as an extension is what enables localization of theme
-   strings in your translated output. If these strings are not translated in
-   your output, either we lack the localized strings for your locale, or you
-   are using an old version of the theme.
-
-   ..
-      comment about this note: it's possibly not necessary to add the theme as an extension.
-      Rather, this is an issue caused by setting html_theme_path.
-      See: https://github.com/readthedocs/readthedocs.org/pull/9654
-
-
 .. _howto_upgrade:
 
 How to upgrade
@@ -55,6 +37,5 @@ Otherwise, pip will ignore pre-releases. Add for instance ``sphinx-rtd-theme==1.
 .. tip::
     We recommend that you pin the version of Sphinx that your project is built with.
     We won't release sphinx-rtd-theme without marking its compatibility with Sphinx. So if you do not pin ``sphinx-rtd-theme`` itself, you will always get the *latest compatible* release.
-    
-    More information is available in Read the Docs' documentation on :doc:`rtd:guides/reproducible-builds`.
 
+    More information is available in Read the Docs' documentation on :doc:`rtd:guides/reproducible-builds`.

setup.cfg

@@ -59,6 +59,7 @@ dev =
 	wheel
 	twine
 
+# https://www.sphinx-doc.org/en/master/development/html_themes/index.html#distribute-your-theme-as-a-python-package
 [options.entry_points]
 sphinx.html_themes = 
 	sphinx_rtd_theme = sphinx_rtd_theme