doc: add development process part

docs/SUMMARY.md

@@ -16,6 +16,7 @@
 ## TEN framework
 
 * [Overview](ten_framework/concept_overview.md)
+* [Development Process](ten_framework/development_process.md)
 * [Preparation](ten_framework/preparation.md)
 * [Version System](ten_framework/version_system.md)
 * [Metadata System](ten_framework/metadata_system.md)

docs/ten_framework/development_process.md

@@ -0,0 +1,20 @@
+# Development Process
+
+Basically, by using the TEN framework to complete the desired scenarios, there are two development approaches or perspectives:
+
+1. From small extensions to large scenarios
+2. From large scenarios to small extensions
+
+**Note:** Regardless of which of these two development approaches you take, you can either write your own extensions from scratch or download pre-built extensions from the TEN cloud store.
+
+In the first approach, **from small extensions to large scenarios**, the development process typically follows these steps:
+
+1. Develop extensions.
+2. Assemble the extensions into a graph, and further create an agent, for example, [TEN-Agent](https://github.com/TEN-framework/TEN-Agent).
+
+In the second approach, **from large scenarios to small extensions**, the development process typically follows these steps:
+
+1. Select the desired agent template, for example, [TEN-Agent](https://github.com/TEN-framework/TEN-Agent).
+2. Replace some of the extensions within the chosen agent template with your own.
+
+In this second development approach, you can ensure that the behavior of the replaced extension matches the original one by using the framework for **standalone testing** of extensions. In this process, the developer only needs to understand concepts related to TEN extensions, including how to independently develop and test a TEN extension. All other TEN-related concepts outside of extension development and testing do not need to be understood, as these concepts are encapsulated within the selected TEN agent.

docs/ten_framework/test_system.md

@@ -2,7 +2,7 @@
 
 ## For Users of the TEN Framework
 
-(To be added.)
+### Standalone Testing of Extension
 
 ## For Developers of the TEN Framework