add comment for missing declarative event handlers

Author: ekashida

libraries/lwc/src/modules/x/withDeclarativeEvent/withDeclarativeEvent.html

@@ -5,6 +5,10 @@
     <div id="caps">{capsHandled}</div>
     <div id="pascal">{pascalHandled}</div>
 
+    <!--
+    LWC compiler throws exceptions for kebab-cased and arbitrarily capitalized events in the
+    template so they are not included here.
+    -->
     <ce-with-event lwc:ref="wc" lwc:external
         onlowercaseevent={handleLowercaseEvent}
     ></ce-with-event>