feat: add extension doc (#463)

docs/SUMMARY.md

@@ -11,6 +11,7 @@
 * [Getting Started](ten_agent/getting_started.md)
 * [Project Structure](ten_agent/project_structure/overview.md)
   * [Understand property.json](ten_agent/project_structure/property_json.md)
+  * [Understand extension folder](ten_agent/project_structure/extension.md)
 * [Run Demo](ten_agent/demo/quickstart.md)
 * [Run Playground](ten_agent/playground/quickstart.md)
   * [Configure Modules](ten_agent/playground/configure_modules.md)

docs/ten_agent/project_structure/extension.md

@@ -0,0 +1,29 @@
+# Understand extension folder
+
+The `ten_packages/extension` folder contains the extension modules. Each extension module is a separate Python/Golang/C++ package.
+
+The extension folder name is often the same as the extension module name, while you can also find the extension module name in the `manifest.json` file under the extension folder. The module name shall be used in the `addon` property of the `property.json` file.
+
+Below is a sample structure of the extension folder:
+
+![Extension Folder Structure](https://github.com/TEN-framework/docs/blob/main/assets/png/extension_folder_struct.png?raw=true)
+
+## Extension Common Files
+
+- manifest.json: This file contains the metadata of the extension. It includes the extension name, version, properties, and apis (data, audio_frame, video_frame).
+- property.json: This file contains the default properties of the extension. It is used to define the default configuration of the extension.
+
+## Python Extension
+
+- extension.py: This file contains the main logic of the extension. It usually contains the core implementation of the extension.
+- requirements.txt: This file contains the Python dependencies required by the extension. Dependencies specified in this file will be installed automatically when you run `task use`.
+
+## Golang Extension
+
+- <xxx>_extension.go: This file contains the main logic of the extension. It usually contains the core implementation of the extension.
+- go.mod: This file contains the Go module definition. It specifies the module name and the dependencies of the extension.
+
+## C++ Extension
+
+- src/main.cc: This file contains the main logic of the extension. It usually contains the core implementation of the extension.
+- BUILD.gn: This file contains the build configuration of the extension. It specifies the target name and dependencies of the extension.

docs/ten_agent/project_structure/property_json.md

@@ -35,7 +35,7 @@ The `property` section of a node contains the configuration of the extension. It
 }
 ```
 
-![Property JSON nodes](https://github.com/TEN-framework/docs/blob/main/assets/png/property_json_nodes.png?raw=true)
+![Property JSON nodes](https://github.com/TEN-framework/docs/blob/main/assets/png/property_json_connections.png?raw=true)
 
 #### Read environment variables
 
@@ -71,6 +71,6 @@ The `connections` section contains the list of connections between nodes. Each c
 }
 ```
 
-![Property JSON Connections](https://github.com/TEN-framework/docs/blob/main/assets/png/property_json_connections.png?raw=true)
+![Property JSON Connections](https://github.com/TEN-framework/docs/blob/main/assets/png/property_json_nodes.png?raw=true)
 
-In the above example, we are connecting `agora_rtc` extension to `deepgram_asr` extension. The `agora_rtc` extension is sending `pcm_frame` data to `deepgram_asr` extension.
+In the above example, we are connecting `agora_rtc` extension to `deepgram_asr` extension. The `agora_rtc` extension is sending `pcm_frame` data to `deepgram_asr` extension.