Add content projection for warning

Author: Emmanuel Garcia

iron-component-page.html

@@ -227,6 +227,7 @@
             <div id="catalog-heading" catalog-only>
               <h2><span>[[active]]</span> <span class="version" hidden$="[[!version]]">[[version]]</span></h2>
             </div>
+            <content></content>
             <iron-doc-viewer prefix="[[_fragmentPrefix]]" id="viewer" descriptor="{{_activeDescriptor}}"
               on-iron-doc-viewer-component-selected="_handleComponentSelectedEvent"></iron-doc-viewer>
             <div id="nodocs" hidden$="[[_activeDescriptor]]" class="no-docs">