net/url: add example to URL.ResolveReference

Change-Id: I9db1997b8dc7e06e9d124753ead6221470a1edf9
Reviewed-on: https://go-review.googlesource.com/12254Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

src/net/url/example_test.go

@@ -84,3 +84,17 @@ func ExampleURL_opaque() {
 	// Accept-Encoding: gzip
 	//
 }
+
+func ExampleURL_ResolveReference() {
+	u, err := url.Parse("../../..//search?q=dotnet")
+	if err != nil {
+		log.Fatal(err)
+	}
+	base, err := url.Parse("http://example.com/directory/")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(base.ResolveReference(u))
+	// Output:
+	// http://example.com/search?q=dotnet
+}