add a sentence signaling no implied restrictions in supported concept…

… definition

src/intent.html

@@ -316,6 +316,9 @@ <h3 id="intent_using">Using Intent Concepts and Properties</h3>
    <p>A concept is considered a <dfn id="intent_supported_concept">supported concept</dfn> (by the AT)
      when the normalized name, the fixity property, and the arity
      all match an entry in the AT's concept dictionary.
+     This does not exclude implementations which support additional concepts,
+     as well as concepts with many arities, fixities or aliases,
+     as long as they are mapped appropriately.
      The speech hint in the matching entry
      can be used as a guide for the generation of
      specific audio, replacement text or braille renderings, as appropriate.