Add FAQ section. Add toggle button examples.

Author: Guille Paz

README.md

@@ -154,7 +154,7 @@ Then you just include Slideout.js and create a new instance with some options:
 
     <main id="panel">
       <header>
-        <button>☰</button>
+        <button class="toggle-button">☰</button>
         <h2>Panel</h2>
       </header>
     </main>
@@ -167,6 +167,11 @@ Then you just include Slideout.js and create a new instance with some options:
         'padding': 256,
         'tolerance': 70
       });
+
+      // Toggle button
+      document.querySelector('.toggle-button').addEventListener('click', function() {
+        slideout.toggle();
+      });
     </script>
 
   </body>
@@ -249,6 +254,22 @@ $ npm test
 $ npm run hint
 ```
 
+## FAQ
+
+### How to add a toggle button.
+
+```js
+// vanilla js
+document.querySelector('.toggle-button').addEventListener('click', function() {
+  slideout.toggle();
+});
+
+// jQuery
+$('.toggle-button').on('click', function() {
+    slideout.toggle();
+});
+```
+
 ## With ❤ by
 - Guille Paz (Front-end developer | Web standards lover)
 - E-mail: [guille87paz@gmail.com](mailto:guille87paz@gmail.com)