docs: Restore "smart quotes" for quotes

Commit eaae75754d ("docs: turn off "smart quotes" in the HTML build")
disabled conversion of quote marks along with that of dashes.
Despite the short summary, the change affects not only HTML build
but also other build targets including PDF.

However, as "smart quotes" had been enabled for more than half a
decade already, quite a few readers of HTML pages are likely expecting
conversions of "foo" -> “foo” and 'bar' -> ‘bar’.

Furthermore, in LaTeX typesetting convention, it is common to use
distinct marks for opening and closing quote marks.

To satisfy such readers' expectation, restore conversion of quotes
only by setting smartquotes_action [1].

Link: [1] https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-smartquotes_action
Cc: stable@vger.kernel.org  # v6.4
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240225094600.65628-1-akiyks@gmail.com

Documentation/conf.py

@@ -346,9 +346,9 @@ sys.stderr.write("Using %s theme\n" % html_theme)
 html_static_path = ['sphinx-static']
 
 # If true, Docutils "smart quotes" will be used to convert quotes and dashes
-# to typographically correct entities.  This will convert "--" to "—",
-# which is not always what we want, so disable it.
-smartquotes = False
+# to typographically correct entities.  However, conversion of "--" to "—"
+# is not always what we want, so enable only quotes.
+smartquotes_action = 'q'
 
 # Custom sidebar templates, maps document names to template names.
 # Note that the RTD theme ignores this