Merge branch '3.4' into 4.2

* 3.4:
  Refactor comment
  remove invalid array type
  fix varnish comment

Author: javiereguiluz

http_cache/varnish.rst

@@ -134,9 +134,8 @@ using Varnish 3:
     .. code-block:: varnish3
 
         sub vcl_fetch {
-            /* By default, Varnish3 ignores Cache-Control: no-cache and private
-               https://www.varnish-cache.org/docs/3.0/tutorial/increasing_your_hitrate.html#cache-control
-             */
+            // By default, Varnish3 ignores Cache-Control: no-cache and private
+            // https://www.varnish-cache.org/docs/3.0/tutorial/increasing_your_hitrate.html#cache-control
             if (beresp.http.Cache-Control ~ "private" ||
                 beresp.http.Cache-Control ~ "no-cache" ||
                 beresp.http.Cache-Control ~ "no-store"

reference/forms/types/options/group_by.rst.inc

@@ -1,7 +1,7 @@
 group_by
 ~~~~~~~~
 
-**type**: ``array``, ``callable`` or ``string`` **default**: ``null``
+**type**: ``string`` or ``callable`` **default**: ``null``
 
 You can group the ``<option>`` elements of a ``<select>`` into ``<optgroup>``
 by passing a multi-dimensional array to ``choices``. See the