Adding curl example

Author: Mark Gibbs

demo/demo/templates/demo_four.html

@@ -41,4 +41,17 @@ <h1>Live Updating</h1>
     {%plotly_app slug="liveoutput-2" ratio=0.5 %}
   </div>
 </div>
+<p>
+</p>
+<p>
+  Any http command
+  can be used to send a message to the apps. This is equiavent to a press of
+  the red button. Other colours can be specified, including yellow, cyan and black in
+  addition to the three named in the LiveInput app.
+</p>
+<div class="card bg-light border-dark">
+  <div class="card-body">
+    curl http://localhost:8000/dpd/views/poke/ -d'{"channel_name":"live_button_counter","label":"named_counts","value":{"click_colour":"red"}}'
+  </div>
+</div>
 {%endblock%}