Fix bug with services extractor

Change-Id: Ifaa6b54f7e9b0b01b4ef6370e6d3c9eeb8db0227
diff --git a/openstack/compute/v2/extensions/os-services/results.go b/openstack/compute/v2/extensions/os-services/results.go
index 17cf1b4..3c6bb04 100644
--- a/openstack/compute/v2/extensions/os-services/results.go
+++ b/openstack/compute/v2/extensions/os-services/results.go
@@ -17,7 +17,7 @@
 
 func ExtractOsServices(r pagination.Page) ([]OsService, error) {
 	var s struct {
-		OsServices []OsService `json:"agents"`
+		OsServices []OsService `json:"services"`
 	}
 	err := (r.(OsServicePage)).ExtractInto(&s)
 	return s.OsServices, err