Update an example test

Author: mdmintz

examples/xpath_test.py

@@ -7,4 +7,5 @@ def test_xpath(self):
         self.assert_element('//h1[(text()="Demo Page")]')
         self.type('//*[@id="myTextInput"]', "XPath Test!")
         self.click('//button[starts-with(text(),"Click Me")]')
+        self.assert_element('//button[contains(., "Purple")]')
         self.assert_text("SeleniumBase", '//table/tbody/tr[1]/td[2]/h2')