Merge pull request #17 from sugarshop/readme

feat: add design doc to README.md

README.md

@@ -3,6 +3,13 @@ A general-purpose API gateway for microservices to provide an HTTP endpoint, nam
 
 The project uses [gin](https://github.com/gin-gonic/gin) as the `web` framework for the public access gateway layer.
 
+# Design Doc
+
+- [Wiki Page](https://gamma.app/public/ChattyAI-l79uftz5bxwbdd8?mode=doc)
+- [GPT API Doc](https://renaissancelabs101.notion.site/API-Access-ea86d8bd0e1345799db00bef03a92151?pvs=4)
+- [Subscription Design Doc](https://renaissancelabs101.notion.site/Subscription-0ea7aa61c2514dafac72ea1764766fd0?pvs=4)
+- [Comprehensive Cost Analyze Doc](https://renaissancelabs101.notion.site/Comprehensive-Cost-Analyze-of-Chatty-AI-System-b417ebe28a8542fe8bec4ee6f90438bb?pvs=4)
+
 ## Layers
 
 The project is divided into the following layers: