add the low level api documentation

Handbook/src/SUMMARY.md

@@ -56,8 +56,8 @@ Welcom to the SenseGlove Unreal Engine Handbook!
 
 # 🔌 Low-Level API
 
-- [Blueprints Low-Level API](low-level-api/blueprints.md)
-- [C++ Low-Level API](low-level-api/cpp.md)
+- [Low-Level Blueprints API](low-level-api/blueprints.md)
+- [Low-Level C++ API](low-level-api/cpp.md)
 
 
 # 📜 License

Handbook/src/low-level-api/blueprints.md

@@ -0,0 +1,13 @@
+# Low-level Blueprint API
+
+Unfortunately, due to Unreal Engine's limited availability of automated documentation generation tools, there is no updated online documentation for the SenseGlove Blueprint API. However, this does not mean that no documentation is available. In fact, most of the Blueprint code is already documented within the relevant header files. Any modules with the `Kismet` postfix in the name contain the Blueprint documentation. For example, the Blueprint documentation for the `Core` module can be found inside the `Source/SenseGloveCoreKismet/Public/SGCoreKismet` directory.
+
+There is also an [outdated Blueprint documentation hosted on GitLab](https://senseglove.gitlab.io/unreal-blueprint-docs/). This documentation was generated for the early releases of the plugin using [kamrann/KantanDocGenPlugin](https://github.com/kamrann/KantanDocGenPlugin) and [kamrann/KantanDocGenTool](https://github.com/kamrann/KantanDocGenTool), which is no longer maintained.
+
+Efforts are ongoing to generate comprehensive documentation using [PsichiX/unreal-doc](https://crates.io/crates/unreal-doc), but progress has been hindered by various [known issues](https://github.com/PsichiX/unreal-doc/issues).
+
+There are also other outdated materials that might still be partially relevant. These include [an example Unreal Engine Blueprint project](https://dev.azure.com/SenseGlove/_git/SenseGlove-Unreal-SGPlaygroundBP) and [a video tutorial](https://www.youtube.com/embed/9ICAH2ZUvVk):
+
+<div style="margin: 0 auto; width: 560px;">
+<iframe width="560" height="315" src="https://www.youtube.com/embed/9ICAH2ZUvVk" frameborder="0" allowfullscreen></iframe>
+</div>

Handbook/src/low-level-api/cpp.md

@@ -0,0 +1,13 @@
+# Low-level C++ API
+
+Due to Unreal Engine's limited availability of automated documentation generation tools, there is no updated online documentation for the SenseGlove Unreal Engine C++ API. However, this does not mean that no documentation is available. A significant portion of the API is documented within the relevant header files. For example, the C++ API documentation for the `Core` module can be found inside the `Source/SenseGloveCore/Public/SGCore` directory.
+
+Efforts are ongoing to generate comprehensive documentation using [PsichiX/unreal-doc](https://crates.io/crates/unreal-doc), but progress has been hindered by various [known issues](https://github.com/PsichiX/unreal-doc/issues).
+
+Nevertheless, since this plugin builds on top of the [SGConnect](https://senseglove.gitlab.io/SenseGloveDocs/native/core-api-intro.html#sgconnect) and [SGCoreCpp](https://senseglove.gitlab.io/SenseGloveDocs/native/core-api-intro.html#sgcorecpp) third-party C++ libraries, the [upstream documentation](https://senseglove.gitlab.io/SenseGloveDocs/native/cpp-reference.html) provides detailed information on various aspects of the underlying SenseGlove C++ API.
+
+There are also other outdated materials that might still be partially relevant. These include [an example Unreal Engine C++ project](https://dev.azure.com/SenseGlove/_git/SenseGlove-Unreal-SGPlaygroundCpp) and [a video tutorial](https://www.youtube.com/embed/9ICAH2ZUvVk):
+
+<div style="margin: 0 auto; width: 560px;">
+<iframe width="560" height="315" src="https://www.youtube.com/embed/9ICAH2ZUvVk" frameborder="0" allowfullscreen></iframe>
+</div>