doc: Add more notes about app development

Signed-off-by: Huaqi Fang <578567190@qq.com>

doc/source/develop/appdev.rst

@@ -29,6 +29,13 @@ To develop a Nuclei SDK application from scratch, you can do the following steps
        include $(NUCLEI_SDK_ROOT)/Build/Makefile.base
 
 3. Copy or create your application code in new created directory.
+
+   .. note::
+
+      * If you just want to SoC related resource, you can include header file ``nuclei_sdk_soc.h`` in your application code.
+      * If you just want to SoC and Board related resource, you can include header file ``nuclei_sdk_hal.h`` in your application code.
+      * For simplity, we recomment you to use ``nuclei_sdk_hal.h`` header file
+
 4. Follow :ref:`develop_buildsystem` to change your application Makefile.
 
 .. _develop_appdev_addsrc:

doc/source/quickstart.rst

@@ -588,7 +588,10 @@ There are several ways to achieve it, see as below:
 
 .. note::
 
-    Please refer to :ref:`develop_appdev` and :ref:`develop_buildsystem` for more information.
+    * Please refer to :ref:`develop_appdev` and :ref:`develop_buildsystem` for more information.
+    * If you want to access SoC related APIs, please use ``nuclei_sdk_soc.h`` header file.
+    * If you want to access SoC and board related APIs, please use ``nuclei_sdk_hal.h`` header file.
+    * For simplified application development, you can use ``nuclei_sdk_hal.h`` directly.
 
 Advanced Usage
 --------------