Rename 2 documentation files (#3567)

* 2 file renames

Installation-Windows —> Installation-Anacondo-Windows to be clearer that it’s about Anaconda on Windows and not just Windows.

index.md —> com.unity.ml-agents.md to be inline with package requirements.

docs/Installation.md

 on installing it.
 
 Although we do not provide support for Anaconda installation on Windows, the previous
-[Windows Anaconda Installation (Deprecated) guide](Installation-Windows.md)
+[Windows Anaconda Installation (Deprecated) guide](Installation-Anaconda-Windows.md)
 is still available.
 
 ### Clone the ML-Agents Toolkit Repository

docs/Limitations.md

 # Limitations
 
 See the package-specific Limitations pages:
-* [Unity `com.unity.mlagents` package](../com.unity.ml-agents/Documentation~/index.md)
+* [Unity `com.unity.mlagents` package](../com.unity.ml-agents/Documentation~/com.unity.ml-agents.md)
 * [`mlagents` Python package](../ml-agents/README.md)
 * [`mlagents_envs` Python package](../ml-agents-envs/README.md)
 * [`gym_unity` Python package](../gym-unity/README.md)

docs/Readme.md

 * [Training on the Cloud with Amazon Web Services](Training-on-Amazon-Web-Service.md)
 * [Training on the Cloud with Microsoft Azure](Training-on-Microsoft-Azure.md)
 * [Using Docker](Using-Docker.md)
-* [Windows Anaconda Installation](Installation-Windows.md)
+* [Windows Anaconda Installation](Installation-Anaconda-Windows.md)

docs/localized/KR/docs/Installation.md

 </p>
 
 ## Windows 사용자
-Windows에서 환경을 설정하기 위해, [세부 사항](Installation-Windows.md)에 설정 방법에 대해 작성하였습니다.
+Windows에서 환경을 설정하기 위해, [세부 사항](Installation-Anaconda-Windows.md)에 설정 방법에 대해 작성하였습니다.
 Mac과 Linux는 다음 가이드를 확인해주십시오.
 
 ## Mac 또는 Unix 사용자

docs/localized/zh-CN/docs/Installation.md

 
 ### Windows 用户
 
-如果您是刚接触 Python 和 TensorFlow 的 Windows 用户，请遵循[此指南](/docs/Installation-Windows.md)来设置 Python 环境。
+如果您是刚接触 Python 和 TensorFlow 的 Windows 用户，请遵循[此指南](/docs/Installation-Anaconda-Windows.md)来设置 Python 环境。
 
 ### Mac 和 Unix 用户