fix java example for static file-system example

Updated the Java static file-system route example to match the corrent Kotlin example. Java read `Paths.get("static")` instead of the correct `Paths.get("www")` as in the Kotlin code example.

Author: agrothe

docs/asciidoc/static-files.adoc

@@ -29,7 +29,7 @@ supports classpath and file-system resources.
 [source, java, role="primary"]
 ----
 {
-  assets("/static/*", Paths.get("static")); <1>
+  assets("/static/*", Paths.get("www")); <1>
 }
 ----