Fix spelling in demo (#5)

* Fix spelling in demo

* Fix spelling in HTML

demo/scripts/demo.js

@@ -28,7 +28,7 @@ document.addEventListener("DOMContentLoaded", function () {
       element: '#name_driver',
       popover: {
         title: 'Why Driver?',
-        description: 'Because it let\'s you drive the user across the page',
+        description: 'Because it lets you drive the user across the page',
         position: 'bottom',
       },
     },

index.html

@@ -154,7 +154,7 @@ driver.highlight({
 </code></pre>
     </div>
 
-    <p class="top-20">And of-course it can be any valid HTML.</p>
+    <p class="top-20">And of course it can be any valid HTML.</p>
 
     <hr class="hr__fancy">