fix literal formatting

bicpi · bicpi · commit 50f89f98d866 · 2013-12-16T06:23:29.000+01:00
diff --git a/book/http_cache.rst b/book/http_cache.rst
@@ -385,7 +385,7 @@ header when none is set by the developer by following these rules:
 * If ``Cache-Control`` is empty (but one of the other cache headers is present),
   its value is set to ``private, must-revalidate``;
 
-* But if at least one ``Cache-Control`` directive is set, and no 'public' or
+* But if at least one ``Cache-Control`` directive is set, and no ``public`` or
   ``private`` directives have been explicitly added, Symfony2 adds the
   ``private`` directive automatically (except when ``s-maxage`` is set).
 
