Added a section in lists.html for the contains method

docs/lists.html

@@ -125,6 +125,13 @@
 	var v1 = list.pop();	// pop 100
 	var v2 = list.pop();	// pop 50
 			</code></pre>
+
+			<h4 class="section-h4">List Contains</h4>
+			<p>The List class implements the contains methods as a convenient way to check for the existance of a value in a list:</p>
+			<pre><code class="swift">
+	var list = [1, 2, "Hello", 3.1415, true];
+	return list.contains(3.1415); // Returns: true
+			</code></pre>
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