Update comment for routes request definition (#735)

Author: willum070

samples/routes-get-directions/index.ts

@@ -77,7 +77,7 @@ async function initMap(): Promise<void> {
   // [END maps_routes_get_directions_request_pluscode]
 
   // [START maps_routes_get_directions_request_simple]
-  // Define a simple request.
+  // Define a routes request.
   const request = {
     origin: 'Mountain View, CA',
     destination: 'San Francisco, CA',