Fix readme 's wrong link (#1500)

* fix wrong link add add reference repo link

README.md

@@ -100,7 +100,7 @@ The tool dispatches and runs trial jobs generated by tuning algorithms to search
           <li><a href="docs/en_US/Tuner/BuiltinTuner.md#BOHB">BOHB</a></li>
           <li><a href="docs/en_US/Tuner/BuiltinTuner.md#GPTuner">GP Tuner</a></li>
           </ul>
-          <li><b>Tuner for <a href="docs/en_US/CommunitySharings/NasComparision.md">NAS</a></b></li>
+          <li><b>Tuner for <a href="docs/en_US/AdvancedFeature/GeneralNasInterfaces.md">NAS</a></b></li>
           <ul>
           <li><a href="docs/en_US/Tuner/BuiltinTuner.md#NetworkMorphism">Network Morphism</a></li>
           <li><a href="examples/tuners/enas_nni/README.md">ENAS</a></li>
@@ -345,11 +345,14 @@ Before providing your hacks, you can review the [Contributing Instruction](docs/
 * [Implement customized TrainingService](docs/en_US/TrainingService/HowToImplementTrainingService.md)
 
 
-## **External Repositories**
-Now we have some external usage examples run in NNI from our contributors. Thanks our lovely contributors. And welcome more and more people to join us!
-* Run [ENAS](examples/tuners/enas_nni/README.md) in NNI
-* Run [Neural Network Architecture Search](examples/trials/nas_cifar10/README.md) in NNI 
-* [Automatic Feature Engineering](examples/trials/auto-feature-engineering/README.md) in NNI
+## **External Repositories and References**
+With authors' permission, we listed a set of NNI usage examples and relevant articles.
+
+* **Repo** - Run [ENAS](examples/tuners/enas_nni/README.md) with NNI
+* **Repo** - Run [Neural Network Architecture Search](examples/trials/nas_cifar10/README.md) with NNI 
+* **Repo** - [Automatic Feature Engineering](examples/trials/auto-feature-engineering/README.md) with NNI 
+* **Repo** - [Hyperparameter Tuning for Matrix Factorization](https://github.com/microsoft/recommenders/blob/master/notebooks/04_model_select_and_optimize/nni_surprise_svd.ipynb) with NNI
+* **Blog (in Chinese)** - [AutoML tools (Advisor, NNI and Google Vizier) comparison by @gaocegege - 总结与分析 section of design and implementation of kubeflow/katib](http://gaocegege.com/Blog/机器学习/katib-new)
 
 ## **Feedback**
 * Discuss on the NNI [Gitter](https://gitter.im/Microsoft/nni?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) in NNI