fix: all link broken and enable Version-Awareness in README and README-Cn (vesoft-inc#2476)

* fix: all link broken in README and README-Cn

* fix: note links for v1.*

* Version awareness links and notices added

* Addressed the how-to links to community repo instead

Co-authored-by: Jamie-VESoft <[email protected]>

* Removed 2.* URLs before we have a Latest Alias on Docs

* fixed how-to-contribute link

* Update README-CN.md

* Address Joe's comments

* Update README-CN.md

Co-authored-by: wey-gu <[email protected]>
Co-authored-by: Jamie-VESoft <[email protected]>
Co-authored-by: cooper-lzy <[email protected]>

Author: 4 people

CONTRIBUTING.md

@@ -1,3 +1,3 @@
 # CONTRIBUTING
 
-See [How to contribute](https://docs.nebula-graph.io/manual-EN/4.contributions/how-to-contribute/) for details about how to contribute to **Nebula Graph**.
+See [How to contribute](https://github.com/vesoft-inc/nebula-community/blob/master/Contributors/how-to-contribute.md) for details about how to contribute to **Nebula Graph**.

README-CN.md

@@ -20,6 +20,14 @@
   </a>
 </p>
 
+## 关于这个 Repo
+
+当前 Repo(https://github.com/vesoft-inc/nebula) 是 Nebula Graph 的旧版本（v1.x）仓库。
+
+从新版本（v2.x）开始，Nebula Graph 的代码被分到了三个仓库中： [nebula-graph](https://github.com/vesoft-inc/nebula-graph)，[nebula-common](https://github.com/vesoft-inc/nebula-common) 和 [nebula-storage](https://github.com/vesoft-inc/nebula-storage)。
+
+我们推荐您从访问 [nebula-graph](https://github.com/vesoft-inc/nebula-graph) 开始，您可以在该仓库内直接下载 release 版本。
+
 # Nebula Graph 是什么
 
 **Nebula Graph** 是一款开源的图数据库，擅长处理千亿个顶点和万亿条边的超大规模数据集。
@@ -43,12 +51,19 @@
 
 ## 快速使用
 
-请查看[快速使用手册](https://docs.nebula-graph.com.cn/manual-CN/4.contributions/how-to-contribute/)，开始使用 **Nebula Graph**。
+请查看[快速入门](https://docs.nebula-graph.com.cn/master/2.quick-start/1.quick-start-workflow/)，开始使用 **Nebula Graph**。
 
-在开始使用 **Nebula Graph** 之前，必须通过[编译源码](https://docs.nebula-graph.com.cn/manual-CN/3.build-develop-and-administration/1.build/1.build-source-code/)，[rpm/deb 包](https://docs.nebula-graph.com.cn/manual-CN/3.build-develop-and-administration/2.install/1.install-with-rpm-deb/) 或者 [docker compose](https://github.com/vesoft-inc/nebula-docker-compose/blob/master/README_zh-CN.md) 方式安装 **Nebula Graph**。您也可以观看[视频](https://space.bilibili.com/472621355)学习如何安装 **Nebula Graph**。
+在开始使用 **Nebula Graph** 之前，除了参考文档，您也可以观看[视频](https://space.bilibili.com/472621355)学习如何安装 **Nebula Graph**。
 
 如果您遇到任何问题，请前往 Nebula Graph [官方论坛](https://discuss.nebula-graph.com.cn) 提问。
 
+>**注意**
+>
+>如果您想使用旧版（v1.x）Nebula Graph，可以参考如下链接：
+>- [Getting started](https://docs.nebula-graph.com.cn/1.2.1/manual-CN/1.overview/2.quick-start/1.get-started/)
+>- [installing source code](https://docs.nebula-graph.com.cn/1.2.1/manual-CN/3.build-develop-and-administration/1.build/1.build-source-code/)
+>- [rpm/deb packages](https://docs.nebula-graph.com.cn/1.2.1/manual-CN/3.build-develop-and-administration/2.install/1.install-with-rpm-deb/)
+
 ## 文档
 
 * [简体中文](https://docs.nebula-graph.com.cn/)
@@ -81,7 +96,7 @@
 **Nebula Graph** 是一个完全开源的项目，欢迎开源爱好者通过以下方式参与到 **Nebula Graph** 社区：
 
 * 从标记为 [good first issues](https://github.com/vesoft-inc/nebula/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) 的问题入手
-* 贡献代码，详情请参见 [如何贡献](https://docs.nebula-graph.com.cn/manual-CN/4.contributions/how-to-contribute/)
+* 贡献代码，详情请参见 [如何贡献](https://github.com/vesoft-inc/nebula-community/blob/master/Contributors/how-to-contribute.md)
 * 直接在GitHub上提 [Issue](https://github.com/vesoft-inc/nebula/issues)
 
 ## 获取帮助 & 联系方式

README.md

@@ -22,6 +22,13 @@
   <br>
 </p>
 
+## About this Repo
+
+Please note that this repo is only for Nebula Graph `v1.*.*`.
+
+From `v2.*.*`, which was already GA in 2021 April, Nebula Graph's core codebases are [nebula-graph](https://github.com/vesoft-inc/nebula-graph), [nebula-common](https://github.com/vesoft-inc/nebula-common) and [nebula-storage](https://github.com/vesoft-inc/nebula-storage), it's recommended to start from the repo: [nebula-graph](https://github.com/vesoft-inc/nebula-graph).
+
+
 # What is Nebula Graph
 
 **Nebula Graph** is an open-source graph database capable of hosting super large-scale graphs with billions of vertices (nodes) and trillions of edges, with milliseconds of latency. It delivers enterprise-grade high performance to simplify the most complex data sets imaginable into meaningful and useful information.
@@ -41,12 +48,20 @@ Compared with other graph database solutions, **Nebula Graph** has the following
 
 ## Quick start
 
-Read the [Getting started](https://docs.nebula-graph.io/manual-EN/1.overview/2.quick-start/1.get-started/) guide to quickly get going with **Nebula Graph**.
+Read the `Getting started` from [docs](https://docs.nebula-graph.io/) to quickly get going with **Nebula Graph**.
 
-Please note that you must install **Nebula Graph** by [installing source code](https://docs.nebula-graph.io/manual-EN/3.build-develop-and-administration/1.build/1.build-source-code/), [rpm/deb packages](https://docs.nebula-graph.io/manual-EN/3.build-develop-and-administration/2.install/1.install-with-rpm-deb/) or [docker compose](https://github.com/vesoft-inc/nebula-docker-compose), before you can actually start using it. If you prefer a video tutorial, visit our [YouTube channel](https://www.youtube.com/channel/UC73V8q795eSEMxDX4Pvdwmw).
+For Nebula Graph Installation, in addition to referring to the docs to deploy from one of the three options: source code, RPM/DEB package, or Docker Compose, if you prefer a video tutorial, please check out our [YouTube channel](https://www.youtube.com/channel/UC73V8q795eSEMxDX4Pvdwmw).
 
 In case you encounter any problem, be sure to ask us on our [official forum](https://discuss.nebula-graph.io).
 
+>**Note**
+>
+>For the users from the legacy `v1.*.*`, please reach out to the following links:
+>- [Getting started](https://docs.nebula-graph.io/1.2.0/manual-EN/1.overview/2.quick-start/1.get-started/)
+>- [installing from source code](https://docs.nebula-graph.io/1.2.0/manual-EN/3.build-develop-and-administration/1.build/1.build-source-code/)
+>- [rpm/deb packages](https://docs.nebula-graph.io/1.2.0/manual-EN/3.build-develop-and-administration/2.install/1.install-with-rpm-deb/)
+
+
 ## Documentation
 
 * [English](https://docs.nebula-graph.io/)
@@ -79,7 +94,7 @@ In order to prevent cloud providers from monetizing the project without contribu
 Contributions are warmly welcomed and greatly appreciated. Here are a few ways you can contribute:
 
 * Start by some [good first issues](https://github.com/vesoft-inc/nebula/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
-* Submit Pull Requests to us. See [how-to-contribute](https://docs.nebula-graph.io/manual-EN/4.contributions/how-to-contribute/).
+* Submit Pull Requests to us. See [how-to-contribute](https://github.com/vesoft-inc/nebula-community/blob/master/Contributors/how-to-contribute.md).
 
 ## Getting help & Contact
 
@@ -92,4 +107,4 @@ In case you encounter any problems playing around **Nebula Graph**, please reach
 
 If you like **Nebula Graph**, please leave us a star.<a href="http://githubbadges.com/star.svg?user=vesoft-inc&repo=nebula&style=default">
     <img src="http://githubbadges.com/star.svg?user=vesoft-inc&repo=nebula&style=default" alt="nebula star"/>
-  </a>
+  </a>