Fix url of balzeface yaml (#800)

docs/en/model_zoo_en.md

@@ -190,7 +190,7 @@ Dataset: WIDER-FACE
 | BlazeFace-NAS  |      -      |     8     |   640    |         83.7/80.7/65.8          |      244       |       21.117     |[model](https://paddlemodels.bj.bcebos.com/object_detection/blazeface_nas.tar) |
 | BlazeFace-NASV2 |    SANAS    |     8     |   640    |         87.0/83.7/68.5          |      389       |       22.558     | [model](https://paddlemodels.bj.bcebos.com/object_detection/blazeface_nas2.tar) |
 
-Note: latency is based on latency_855.txt, the file is test on 855 by PaddleLite。The config of BlazeFace-NASV2 is in [there](https://github.com/PaddlePaddle/PaddleDetection/blob/master/configs/face_detection/blazeface_nas_v2.yml).
+Note: latency is based on latency_855.txt, the file is test on 855 by PaddleLite。The config of BlazeFace-NASV2 is in [there](https://github.com/PaddlePaddle/PaddleDetection/blob/release/2.1/static/configs/face_detection/blazeface_nas_v2.yml).
 
 
 ## 3. Image Segmentation