[docs] Rename docs/index.md to docs/README.md (microsoft#16758)

* Rename docs/index.md to docs/README.md

* Update links to index.md

CHANGELOG.md

@@ -124,7 +124,7 @@ vcpkg (2020.11.01)
     - [(#13488)](https://github.com/microsoft/vcpkg/pull/13488) [vcpkg manifest] Add documentation! (by @strega-nil)
 - [Packaging Github Repos Example: libogg](docs/examples/packaging-github-repos.md)
     - [(#13488)](https://github.com/microsoft/vcpkg/pull/13488) [vcpkg manifest] Add documentation! (by @strega-nil)
-- [Quick Start](docs/index.md)
+- [Quick Start](docs/README.md)
     - [(#13488)](https://github.com/microsoft/vcpkg/pull/13488) [vcpkg manifest] Add documentation! (by @strega-nil)
 - [Manifest files - `vcpkg.json`](docs/maintainers/manifest-files.md)***[NEW]***
     - [(#13488)](https://github.com/microsoft/vcpkg/pull/13488) [vcpkg manifest] Add documentation! (by @strega-nil)
@@ -6983,7 +6983,7 @@ vcpkg (2019.08.31)
       - [(#7950)](https://github.com/microsoft/vcpkg/pull/7950) [vcpkg install] Enable Download Mode ⏬
 
 #### The following documentation has been updated:
-- [Index](docs/index.md)
+- [Index](docs/README.md)
     - [(#7506)](https://github.com/microsoft/vcpkg/pull/7506) Update tests, and add documentation!
     - [(#7821)](https://github.com/microsoft/vcpkg/pull/7821) [vcpkg docs] More tool maintainer docs! 🐱‍👤
 - [Tool maintainers: Testing](docs/tool-maintainers/testing.md) ***[NEW]***
@@ -8432,7 +8432,7 @@ vcpkg (2019.6.30)
 - [CONTROL files](docs/maintainers/control-files.md#Homepage)
     - [(#6844)](https://github.com/Microsoft/vcpkg/pull/6844) [vcpkg] Add optional 'Homepage' field to CONTROL
     - [(#6871)](https://github.com/Microsoft/vcpkg/pull/6871) [docs] Add maintainer guidelines
-- [index](docs/index.md)
+- [index](docs/README.md)
     - [(#6871)](https://github.com/Microsoft/vcpkg/pull/6871) [docs] Add maintainer guidelines
 - [Portfile helper functions](docs/maintainers/portfile-functions.md)
     - [(#7039)](https://github.com/Microsoft/vcpkg/pull/7039) [docs]Update cmake docs

README_es.md

@@ -19,7 +19,7 @@ una vez instalado Vcpkg puede ejecutar `vcpkg help`, o
 * Github: [https://github.com/microsoft/vcpkg](https://github.com/microsoft/vcpkg)
 * Slack: [https://cppalliance.org/slack/](https://cppalliance.org/slack/), en el canal #vcpkg
 * Discord: [\#include \<C++\>](https://www.includecpp.org), en el canal #🌏vcpkg
-* Docs: [Documentación](docs/index.md)
+* Docs: [Documentación](docs/README.md)
 
 [![Estado de compilación](https://dev.azure.com/vcpkg/public/_apis/build/status/microsoft.vcpkg.ci?branchName=master)](https://dev.azure.com/vcpkg/public/_build/latest?definitionId=29&branchName=master)
 
@@ -360,7 +360,7 @@ según la terminal que use, luego reinicie la consola.
 
 ## Ejemplos
 
-ver la [documentación](docs/index.md) para tutoriales específicos, incluyendo
+ver la [documentación](docs/README.md) para tutoriales específicos, incluyendo
 [instalando y usando un paquete](docs/examples/installing-and-using-packages.md),
 [agregando un nuevo paquete desde un archivo comprimido](docs/examples/packaging-zipfiles.md),
 [agregando un nuevo paquete desde un repositorio en GitHub](docs/examples/packaging-github-repos.md).

README_fr.md

@@ -14,7 +14,7 @@ Pour une description des commandes disponibles, quand vous avez installé vcpkg,
 * Github: [https://github.com/microsoft/vcpkg](https://github.com/microsoft/vcpkg)
 * Slack: [https://cppalliance.org/slack/](https://cppalliance.org/slack/), the #vcpkg channel
 * Discord: [\#include \<C++\>](https://www.includecpp.org), le canal #🌏vcpkg
-* Docs: [Documentation](docs/index.md)
+* Docs: [Documentation](docs/README.md)
 
 [![Build Status](https://dev.azure.com/vcpkg/public/_apis/build/status/microsoft.vcpkg.ci?branchName=master)](https://dev.azure.com/vcpkg/public/_build/latest?definitionId=29&branchName=master)
 
@@ -274,7 +274,7 @@ selon le shell que vous utilisez, puis redémarrez la console.
 
 # Exemples
 
-Lisez la [documentation](doc/index.md) pour des instructions plus spécifiques ainsi que [l'installation et l'utilisation des paquets](docs/examples/installing-and-using-packages.md),
+Lisez la [documentation](doc/README.md) pour des instructions plus spécifiques ainsi que [l'installation et l'utilisation des paquets](docs/examples/installing-and-using-packages.md),
 [ajouter un nouveau paquet depuis un fichier zip](docs/examples/packaging-zipfiles.md),
 et [ajouter un nouveau paquet depuis un dépôt GitHub](docs/examples/packaging-github-repos.md).
 

README_ko_KR.md

@@ -11,7 +11,7 @@ vcpkg 사용을 시작하는 방법은 [시작하기](#시작하기) 섹션을 
 * Github: [https://github.com/microsoft/vcpkg](https://github.com/microsoft/vcpkg)
 * Slack: [https://cppalliance.org/slack/](https://cppalliance.org/slack/), #vcpkg 채널
 * Discord: [\#include \<C++\>](https://www.includecpp.org), #🌏vcpkg 채널
-* Docs: [Documentation](docs/index.md)
+* Docs: [Documentation](docs/README.md)
 
 [![Build Status](https://dev.azure.com/vcpkg/public/_apis/build/status/microsoft.vcpkg.ci?branchName=master)](https://dev.azure.com/vcpkg/public/_build/latest?definitionId=29&branchName=master)
 
@@ -294,7 +294,7 @@ $ ./vcpkg integrate bash
 
 # 예제
 
-구체적인 연습은 [문서](docs/index.md)를 참고하세요,
+구체적인 연습은 [문서](docs/README.md)를 참고하세요,
 including [패키지 설치 및 사용](docs/examples/installing-and-using-packages.md),
 [zip 파일에서 새 패키지 추가](docs/examples/packaging-zipfiles.md),
 및 [GitHub 저장소에서 새 패키지 추가](docs/examples/packaging-github-repos.md).

README_zh_CN.md

@@ -12,7 +12,7 @@ Vcpkg 可帮助您在 Windows、 Linux 和 MacOS 上管理 C 和 C++ 库。
 * Github: [https://github.com/microsoft/vcpkg](https://github.com/microsoft/vcpkg)
 * Slack: [https://cppalliance.org/slack/](https://cppalliance.org/slack/)， #vcpkg 频道
 * Discord: [\#include \<C++\>](https://www.includecpp.org)， #🌏vcpkg 频道
-* 文档: [Documentation](docs/index.md)
+* 文档: [Documentation](docs/README.md)
 
 [![当前生成状态](https://dev.azure.com/vcpkg/public/_apis/build/status/microsoft.vcpkg.ci?branchName=master)](https://dev.azure.com/vcpkg/public/_build/latest?definitionId=29&branchName=master)
 
@@ -286,7 +286,7 @@ $ ./vcpkg integrate bash
 
 ## 示例
 
-请查看 [文档](docs/index.md) 获取具体示例，
+请查看 [文档](docs/README.md) 获取具体示例，
 其包含 [安装并使用包](docs/examples/installing-and-using-packages.md)，
 [使用压缩文件添加包](docs/examples/packaging-zipfiles.md)
 和 [从GitHub源中添加一个包](docs/examples/packaging-github-repos.md)。

docs/index.md → docs/README.md

@@ -1,6 +1,6 @@
 ### Quick Start
 
-**The latest version of this documentation is available on [GitHub](https://github.com/Microsoft/vcpkg/tree/master/docs/index.md).**
+**The latest version of this documentation is available on [GitHub](https://github.com/Microsoft/vcpkg/tree/master/docs/README.md).**
 
 Vcpkg helps you manage C and C++ libraries on Windows, Linux and MacOS. This tool and ecosystem are constantly evolving; your involvement is vital to its success!