[#2375] Update documentation for attributes macro

ckan/templates/macros/form.html

@@ -245,6 +245,18 @@
   {% endif %}
 {% endmacro %}
 
+{#
+Builds a space seperated list of html attributes from a dict of key/value pairs.
+Generally only used internally by macros.
+
+attrs - A dict of attribute/value pairs
+
+Example
+
+  {% import 'macros/form.html' as form %}
+  {{ form.attributes({}) }}
+
+#}
 {%- macro attributes(attrs={}) -%}
   {%- for key, value in attrs.items() -%}
     {{ key }}="{{ value }}"