Update README with an example

Author: maael

README.md

@@ -1,2 +1,28 @@
 # html-chain
 A super small (only 2.7kB) javascript library to make html by chaining javascript functions.
+
+## Example
+
+```js
+var test = dom()
+    .add('div', {className: 'container'})
+        .contains('div', {className: 'header'})
+            .contains('h5', {className: 'headerTitle', text: 'This is a header'}).end()
+        .and('div', {className: 'content'})
+            .contains('p', {text: 'This is the content'}).end()
+        .end()
+    .build();
+```
+
+Produces -
+
+```html
+<div class='container'>
+    <div class='header'>
+        <h5 class='headerTitle'>This is a header</h5>
+    </div>
+    <div class='content'>
+        <p>This is the content</p>
+    </div>
+</div>
+```