[TD-4239]<fix>: make github default protocol back to https (#7929)

.gitmodules

 [submodule "src/connector/go"]
 	path = src/connector/go
-	url = git@github.com:taosdata/driver-go.git
+	url = https://github.com/taosdata/driver-go.git
 [submodule "src/connector/grafanaplugin"]
 	path = src/connector/grafanaplugin
-	url = git@github.com:taosdata/grafanaplugin.git
+	url = https://github.com/taosdata/grafanaplugin.git
 [submodule "src/connector/hivemq-tdengine-extension"]
 	path = src/connector/hivemq-tdengine-extension
-	url = git@github.com:taosdata/hivemq-tdengine-extension.git
+	url = https://github.com/taosdata/hivemq-tdengine-extension.git
 [submodule "tests/examples/rust"]
 	path = tests/examples/rust
 	url = https://github.com/songtianyi/tdengine-rust-bindings.git

README-CN.md

@@ -107,6 +107,12 @@ Go 连接器和 Grafana 插件在其他独立仓库，如果安装它们的话
 git submodule update --init --recursive
 ```
 
+如果使用 https 协议下载比较慢，可以通过修改 ~/.gitconfig 文件添加以下两行设置使用 ssh 协议下载。需要首先上传 ssh 密钥到 GitHub，详细方法请参考 GitHub 官方文档。
+```
+[url "git@github.com:"]
+    insteadOf = https://github.com/
+```
+
 ## 构建 TDengine
 
 ### Linux 系统

README.md

@@ -101,6 +101,12 @@ so you should run this command in the TDengine directory to install them:
 git submodule update --init --recursive
 ```
 
+You can modify the file ~/.gitconfig to use ssh protocol instead of https for better download speed. You need to upload ssh public key to GitHub first. Please refer to GitHub official documentation.
+```
+[url "git@github.com:"]
+    insteadOf = https://github.com/
+```
+
 ## Build TDengine
 
 ### On Linux platform