docs: update en contributing (#3398)

CONTRIBUTING.md

@@ -31,7 +31,7 @@ If you cannot find an existing issue that describes your bug or feature, create
 # Writing good bug reports or feature requests
 File a single issue per problem and feature request. Do not enumerate multiple bugs or feature requests in the same issue.
 
-Provide as many information as you think might relevant to the context (thinking the issue is assigning to you, what kinds of info you will need to debug it!!!). To give you a general idea about what kinds of info are useful for developers to dig out the issue, we had provided issue template for you.
+Provide as much information as you think might relevant to the context (thinking the issue is assigning to you, what kinds of info you will need to debug it!!!). To give you a general idea about what kinds of info are useful for developers to dig out the issue, we had provided issue template for you.
 
 Once you had submitted an issue, be sure to follow it for questions and discussions. 
 
@@ -58,11 +58,11 @@ contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additio
 After getting familiar with contribution agreements, you are ready to create your first PR =), follow the NNI developer tutorials to get start:
 
 * We recommend new contributors to start with simple issues: ['good first issue'](https://github.com/Microsoft/nni/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) or ['help-wanted'](https://github.com/microsoft/nni/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22).
-* [NNI developer environment installation tutorial](docs/en_US/Tutorial/SetupNniDeveloperEnvironment.md)
-* [How to debug](docs/en_US/Tutorial/HowToDebug.md)
-* If you have any questions on usage, review [FAQ](https://github.com/microsoft/nni/blob/master/docs/en_US/Tutorial/FAQ.md) first, if there are no relevant issues and answers to your question, try contact NNI dev team and users in [Gitter](https://gitter.im/Microsoft/nni?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) or [File an issue](https://github.com/microsoft/nni/issues/new/choose) on GitHub.
-* [Customize your own Tuner](docs/en_US/Tuner/CustomizeTuner.md)
-* [Implement customized TrainingService](docs/en_US/TrainingService/HowToImplementTrainingService.md)
-* [Implement a new NAS trainer on NNI](docs/en_US/NAS/Advanced.md)
-* [Customize your own Advisor](docs/en_US/Tuner/CustomizeAdvisor.md)
+* [NNI developer environment installation tutorial](docs/en_US/Tutorial/SetupNniDeveloperEnvironment.rst)
+* [How to debug](docs/en_US/Tutorial/HowToDebug.rst)
+* If you have any questions on usage, review [FAQ](https://github.com/microsoft/nni/blob/master/docs/en_US/Tutorial/FAQ.rst) first, if there are no relevant issues and answers to your question, try contact NNI dev team and users in [Gitter](https://gitter.im/Microsoft/nni?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) or [File an issue](https://github.com/microsoft/nni/issues/new/choose) on GitHub.
+* [Customize your own Tuner](docs/en_US/Tuner/CustomizeTuner.rst)
+* [Implement customized TrainingService](docs/en_US/TrainingService/HowToImplementTrainingService.rst)
+* [Implement a new NAS trainer on NNI](docs/en_US/NAS/Advanced.rst)
+* [Customize your own Advisor](docs/en_US/Tuner/CustomizeAdvisor.rst)