Fix a missing line of xml fragment

Closes gh-1461

src/docs/asciidoc/web/web-mvc.adoc

@@ -2578,6 +2578,7 @@ For applications configured with a `web.xml` be sure to update to version 3.0:
 ----
 	<web-app xmlns="http://java.sun.com/xml/ns/javaee"
 		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		xsi:schemaLocation="
 				http://java.sun.com/xml/ns/javaee
 				http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
 		version="3.0">