Update pull_request_template.md

.github/pull_request_template.md

@@ -6,3 +6,7 @@ Please check the follow step before merging this pull request
 - [ ] Review all the code diff by yourself
 - [ ] All models(TensorFLow/Caffe/ONNX/PyTorch) testing passed
 - [ ] Details about your pull request, releated issues
+
+If this PR add new model support, please update `model_zoo.md`
+- [] New Model Supported
+- [] No New Model Supported