docs(extension): add swagger data extension and update documentation

- Add swagger data extension to the extensions list
- Update documentation to include new extension usage

Author: LinuxSuRen

docs/site/content/zh/latest/tasks/extension.md

@@ -31,3 +31,9 @@ atest extension orm
 ```shell
 atest extension orm --registry ghcr.io --timeout 2ms
 ```
+
+想要下载其他类型的插件的话，可以使用下面的命令：
+
+```shell
+atest extension --kind data swagger
+```

extensions/README.md

@@ -11,6 +11,7 @@ Ports in extensions:
 | Monitor | [docker-monitor](https://github.com/LinuxSuRen/atest-ext-monitor-docker) |  |
 | Agent | [collector](https://github.com/LinuxSuRen/atest-ext-collector)           |  |
 | Secret | [Vault](https://github.com/LinuxSuRen/api-testing-vault-extension)       | |
+| Data | [Swagger](https://github.com/LinuxSuRen/atest-ext-data-swagger) | |
 
 ## Contribute a new extension