fix one spelling error in dx-sig responsibilities

sigs/README.md

@@ -37,4 +37,4 @@ in the mailing list. SIG artifacts can be found in the current repository.
 | [Parallel](parallel/README.md) | This SIG is responsible for the development of MindSpore's functionality of automatically finding the efficient parallel strategy for DNN training and inference. | [@dr-orange](https://gitee.com/dr-orange)(chengli7@ustc.edu.cn) |
 | [AdaptiveTraining](adaptivetraining/README.md) | This SIG is to develop an adaptive distributed training system that can train the neural networks in elastic clusters without affecting the convergence. | [@luomai-edin](https://gitee.com/luomai-edin)(luo.mai@outlook.com) |
 | [Serving](serving/README.md) | This SIG is responsible for the development of MindSpore Serving module. | [@xu-yfei](https://gitee.com/xu-yfei) |
-| [DevelopereXperience](dx/README.md) | This SIG is is responsible for improving the experience of those who upstream contribute or develop applications for MindSpore community. | [@jiancao81](https://gitee.com/jiancao81)(cao-jian@cs.sjtu.edu.cn)  [@clement_li](https://gitee.com/clement_li) |
+| [DevelopereXperience](dx/README.md) | This SIG is responsible for improving the experience of those who upstream contribute or develop applications for MindSpore community. | [@jiancao81](https://gitee.com/jiancao81)(cao-jian@cs.sjtu.edu.cn)  [@clement_li](https://gitee.com/clement_li) |