docs: doc-guide: clarify latest theme usage

We have been using the Alabaster theme as the default theme since
Sept. 2022.

Keep the information on the RTD theme around in case someone wants to
try it with the DOCS_THEME environment variable.

Fixes: 26d797f ("docs: update sphinx.rst to reflect the default theme change")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20250519223613.37277-1-rdunlap@infradead.org>

Author: rddunlap

Documentation/doc-guide/sphinx.rst

@@ -42,12 +42,6 @@ with your distributions. In order to do so, it is recommended to install
 Sphinx inside a virtual environment, using ``virtualenv-3``
 or ``virtualenv``, depending on how your distribution packaged Python 3.
 
-.. note::
-
-   #) It is recommended to use the RTD theme for html output. Depending
-      on the Sphinx version, it should be installed separately,
-      with ``pip install sphinx_rtd_theme``.
-
 In summary, if you want to install the latest version of Sphinx, you
 should do::
 
@@ -162,6 +156,12 @@ By default, the "Alabaster" theme is used to build the HTML documentation;
 this theme is bundled with Sphinx and need not be installed separately.
 The Sphinx theme can be overridden by using the ``DOCS_THEME`` make variable.
 
+.. note::
+
+   Some people might prefer to use the RTD theme for html output.
+   Depending on the Sphinx version, it should be installed separately,
+   with ``pip install sphinx_rtd_theme``.
+
 There is another make variable ``SPHINXDIRS``, which is useful when test
 building a subset of documentation.  For example, you can build documents
 under ``Documentation/doc-guide`` by running