Fix documentation test

Author: papandreou

documentation/assertions/string/parsed-as-XML.md

@@ -2,8 +2,7 @@ Parses a string as an XML document using the facilities available in the browser
 
 ```js
 expect(
-    `
-    <?xml version="1.0"?>
+    `<?xml version="1.0"?>
     <content>
       <hello type="greeting">World</hello>
     </content>