refine quick_start doc (#3636)

docs/QUICK_STARTED.md

@@ -2,7 +2,7 @@ English | [简体中文](QUICK_STARTED_cn.md)
 
 # Quick Start
 
-This tutorial fine-tunes a tiny dataset by pretrained detection model for users to get a model and learn PaddleDetection quickly. The model can be trained in around 15min with good performance.
+This tutorial fine-tunes a tiny dataset by pretrained detection model for users to get a model and learn PaddleDetection quickly. The model can be trained in around 20min with good performance.
 
 ## Data Preparation
 

docs/QUICK_STARTED_cn.md

@@ -2,7 +2,7 @@
 
 # 快速开始
 
-为了使得用户能够在很短的时间内快速产出模型，掌握PaddleDetection的使用方式，这篇教程通过一个预训练检测模型对小数据集进行finetune。在P40上单卡大约15min即可产出一个效果不错的模型。
+为了使得用户能够在很短的时间内快速产出模型，掌握PaddleDetection的使用方式，这篇教程通过一个预训练检测模型对小数据集进行finetune。在P40上单卡大约20min即可产出一个效果不错的模型。
 
 ## 数据准备