nixos/make-options-doc: enable smartquotes and replacements

the rest of the nixos manual has them enabled, so we should enable them
here too for consistency.

this changes rendered output pervasively. changes also include quotes in
types (eg in `strings concatenated with "\n"`), but since those are not
code this is probably fine. if not we can probably add a myst role to
inhibit replacements.

nixos/lib/make-options-doc/optionsToDocbook.py

···
             {
                 'maxNesting': 100,   # default is 20
                 'html': False,       # not useful since we target many formats
+                'typographer': True, # required for smartquotes
             },
             renderer_cls=Renderer
         )
···
         self._md.use(container_plugin, name="{.warning}")
         self._md.use(deflist_plugin)
         self._md.use(myst_role_plugin)
+        self._md.enable(["smartquotes", "replacements"])
 
         self._manpage_urls = frozendict(manpage_urls)