pat validation: Add email validation to demo.

Author: thet

src/pat/validation/index.html

@@ -28,6 +28,11 @@
                     <input type="number" name="age" min="16" max="65" required
                 /></label>
 
+                <label
+                    >E-mail
+                    <input type="email" name="email"
+                /></label>
+
                 <fieldset class="group pat-checklist radio">
                     <legend>Favourite colour</legend>
                     <label