put comment for users at top of index.html

index.html

@@ -1627,8 +1627,15 @@ <h1><center> afni_proc.py single subject report <center></h1>
   <!-- top of subj/title info -->
   <div style="text-align: center;">
     <div style="display: inline-block; text-align: left;">
-      <pre><h2>subj: sub-002</h2></pre>
-      <pre><h3>task: task_name</h3></pre>
+      <pre><h2>                          subj: sub-002</h2></pre>
+      <pre><h3>                          task: task_name</h3></pre>
+      <pre><h3>This is a demo of some features within afni_proc.py's APQC HTML.
+Here, you can try out the following:
++ QC rating+comment buttons in the top menu (click and Ctrl+click)
++ "NV" buttons by each dset image, to toggle NiiVue on/off and 
+  explore the datasets interactively (click and scroll; use "c" 
+  over the rendered volume to clip it.)
++ the "HELP" button in the top menu to see more features.</h3></pre>
     </div>
   </div> <!-- bot of subj/title info -->
 </div> <!-- end of title block div -->