Composite Test: Add information about nested forms

Add information for composite pattern test to hopefully
help to not mislead anyone viewing this test, into thinking
that they can nest HTML form elements.

Closes DesignPatternsPHP#264

Author: mcampbell508

Structural/Composite/Tests/CompositeTest.php

@@ -16,6 +16,9 @@ public function testRender()
         $embed->addElement(new Composite\InputElement());
         $form->addElement($embed);
 
+        // This is just an example, in a real world scenario it is important to remember that web browsers do not
+        // currently support nested forms
+
         $this->assertEquals(
             '<form>Email:<input type="text" /><form>Password:<input type="text" /></form></form>',
             $form->render()