describe how to order rooms that don't have an order in their tags

specification/modules/tags.rst

@@ -23,10 +23,13 @@ to order the rooms with a given tag.
 
 Ordering information is given under the ``order`` key as a string. The string
 are compared lexicographically by unicode codepoint to determine which should
-displayed first. So a tag with an ``order`` key of ``"apples"`` would appear
-before a tag with an ``order`` key of ``"oranges"``.
+displayed first. So a room with a tag with an ``order`` key of ``"apples"``
+would appear before a room with a tag with an ``order`` key of ``"oranges"``.
+If a room has a tag without an ``order`` key then it should appear after the
+rooms with that tag that have an ``order`` key.
 
-{{m_tag_event}}
+
+{{m_tag_event}
 
 Client Behaviour
 ----------------