added some missing docs

doc/filters/column.rst

@@ -0,0 +1,27 @@
+``column``
+==========
+
+.. versionadded:: 2.8
+    The ``column`` filter was added in Twig 2.8.
+
+The ``column`` filter returns the values from a single column in the input
+array.
+
+.. code-block:: jinja
+
+    {% set items = [{ 'fruit' : 'apple'}, {'fruit' : 'orange' }] %}
+
+    {% set fruits = items|column('fruit') %}
+
+    {# fruits now contains ['apple', 'orange'] #}
+
+.. note::
+
+    Internally, Twig uses the PHP `array_column`_ function.
+
+Arguments
+---------
+
+* ``name``: The column name to extract
+
+.. _`array_column`: https://secure.php.net/array_column