fix some absolute links to relative. (#733)

README.md

 <p align="center">
-<img src="https://github.com/Microsoft/nni/blob/master/docs/img/nni_logo.png" width="300"/>
+<img src="docs/img/nni_logo.png" width="300"/>
 </p>
 
 -----------
 
-[![MIT licensed](https://img.shields.io/badge/license-MIT-brightgreen.svg)](https://github.com/Microsoft/nni/blob/master/LICENSE)
+[![MIT licensed](https://img.shields.io/badge/license-MIT-brightgreen.svg)](LICENSE)
 [![Build Status](https://msrasrg.visualstudio.com/NNIOpenSource/_apis/build/status/Microsoft.nni)](https://msrasrg.visualstudio.com/NNIOpenSource/_build/latest?definitionId=6)
 [![Issues](https://img.shields.io/github/issues-raw/Microsoft/nni.svg)](https://github.com/Microsoft/nni/issues?q=is%3Aissue+is%3Aopen)
 [![Bugs](https://img.shields.io/github/issues/Microsoft/nni/bug.svg)](https://github.com/Microsoft/nni/issues?q=is%3Aissue+is%3Aopen+label%3Abug)
@@ -18,22 +18,22 @@ The tool dispatches and runs trial jobs generated by tuning algorithms to search
 
 ### **NNI [v0.5.1](https://github.com/Microsoft/nni/releases) has been released!**
 <p align="center">
-  <a href="#nni-v05-has-been-released"><img src="https://github.com/Microsoft/nni/blob/master/docs/img/overview.svg" /></a>
+  <a href="#nni-v05-has-been-released"><img src="docs/img/overview.svg" /></a>
 </p>
 <table>
   <tbody>
     <tr align="center" valign="bottom">
       <td>
         <b>Supported Frameworks</b>
-        <img src="https://github.com/Microsoft/nni/blob/master/docs/img/bar.png"/>
+        <img src="docs/img/bar.png"/>
       </td>
       <td>
         <b>Tuning Algorithms</b>
-        <img src="https://github.com/Microsoft/nni/blob/master/docs/img/bar.png"/>
+        <img src="docs/img/bar.png"/>
       </td>
       <td>
         <b>Training Services</b>
-        <img src="https://github.com/Microsoft/nni/blob/master/docs/img/bar.png"/>
+        <img src="docs/img/bar.png"/>
       </td>
     </tr>
     <tr/>
@@ -204,4 +204,4 @@ Before start coding, review and get familiar with the NNI Code Contribution Guid
 We are in construction of the instruction for [How to Debug](docs/HowToDebug.md), you are also welcome to contribute questions or suggestions on this area.
 
 ## **License** 
-The entire codebase is under [MIT license](https://github.com/Microsoft/nni/blob/master/LICENSE)
+The entire codebase is under [MIT license](LICENSE)

docs/RELEASE.md

@@ -49,7 +49,7 @@
 
 #### Training Service improvements
 
-* Migrate [Kubeflow training service](https://github.com/Microsoft/nni/blob/master/docs/KubeflowMode.md)'s dependency from kubectl CLI to [Kubernetes API](https://kubernetes.io/docs/concepts/overview/kubernetes-api/) client
+* Migrate [Kubeflow training service](KubeflowMode.md)'s dependency from kubectl CLI to [Kubernetes API](https://kubernetes.io/docs/concepts/overview/kubernetes-api/) client
 * [Pytorch-operator](https://github.com/kubeflow/pytorch-operator) support for Kubeflow training service
 * Improvement on local code files uploading to OpenPAI HDFS
 * Fixed OpenPAI integration WebUI bug: WebUI doesn't show latest trial job status, which is caused by OpenPAI token expiration
@@ -115,7 +115,7 @@
   ```
 
 * Support updating max trial number.
-  use `nnictl update --help` to learn more. Or refer to [NNICTL Spec](https://github.com/Microsoft/nni/blob/master/docs/NNICTLDOC.md) for the fully usage of NNICTL.
+  use `nnictl update --help` to learn more. Or refer to [NNICTL Spec](NNICTLDOC.md) for the fully usage of NNICTL.
 
 ### API new features and updates
 

docs/cifar10_examples.md

@@ -77,7 +77,7 @@ nnictl create --config nni/examples/trials/cifar10_pytorch/config.yml
 [2]: https://pytorch.org/
 [3]: https://www.cs.toronto.edu/~kriz/cifar.html
 [4]: https://github.com/Microsoft/nni/tree/master/examples/trials/cifar10_pytorch
-[5]: https://github.com/Microsoft/nni/blob/master/docs/Trials.md
+[5]: Trials.md
 [6]: https://github.com/Microsoft/nni/blob/master/examples/trials/cifar10_pytorch/config.yml
 [7]: https://github.com/Microsoft/nni/blob/master/examples/trials/cifar10_pytorch/config_pai.yml
 [8]: https://github.com/Microsoft/nni/blob/master/examples/trials/cifar10_pytorch/search_space.json

docs/gbdt_example.md

@@ -98,7 +98,7 @@ If you like to tune `num_leaves`, `learning_rate`, `bagging_fraction` and `baggi
 }
 ```
 
-More support variable type you could reference [here](https://github.com/Microsoft/nni/blob/master/docs/SearchSpaceSpec.md).
+More support variable type you could reference [here](SearchSpaceSpec.md).
 
 ### 3.3 Add SDK of nni into your code.