add introductory wording fro example section

Author: davidcarlisle

src/intent.html

@@ -440,7 +440,9 @@ <h4 id="mixing_intent_self_properties">Interpretation of self-properies</h4>
 
    <section class="fold">
      <h4 id="mixing_intent_interpreting_examples">Examples</h4>
-
+     <p>In this section we show some examples using the above interpretation
+       to expand intent expressions.</p>
+       
       <dl>
        <dt>factorial</dt>
        <dd>