fix duplicated word

Author: joaostein

17_http.txt

@@ -386,7 +386,7 @@ the ((DOM)) discussed in link:13_dom.html#dom[Chapter 13], except that
 it doesn't have HTML-specific functionality like the `style` property.
 The object that `responseXML` holds corresponds to the `document`
 object. Its `documentElement` property refers to the outer tag of the
-XML document. In the following document (_example/fruit.xml_), that would
+XML document. In the following document (_example/fruit.xml_), that
 would be the `<fruits>` tag:
 
 [source,application/xml]