Add OpenTelemetry instrumentation with middleware-only approach

pkg/greet/api_v1.go

@@ -45,4 +45,4 @@ func (h *apiV1GreetHandler) handleGreetPath(w http.ResponseWriter, r *http.Reque
 func (h *apiV1GreetHandler) writeJSONResponse(w http.ResponseWriter, message string) {
 	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(map[string]string{"message": message})
-}
+}