docs : add copy for elements demos

_layouts/elements.html

@@ -3,6 +3,10 @@
   <p id="demo-nav"><a href="../index.html">{{ site.name }}</a> Demo</p>
 
   <h1>{{ page.title }}</h1>
+  
+  <section id="copy">
+    <p>Isotope&rsquo;s capabilities are designed to be used together cohesively. You can do it all &mdash; filter, sort, change layout modes, add items &mdash; and Isotope will handle it with ease.</p>
+  </section>
 
   <section id="options" class="clearfix">