docs: update project lists in README files to include web_api

Add the web_api project to the lists of projects in both the English and Chinese
README.md files, providing a brief description and linking to the project's
documentation. Ensure that the formatting and style are consistent with the
existing project entries.

projects/README.md

@@ -5,4 +5,6 @@
 - [llama_index_rag](./llama_index_rag/README.md): Build a lightweight RAG system based on llama_index
 - [gradio_app](./gradio_app/README.md): Build a web app based on gradio
 - [web_demo](./web_demo/README.md): MinerU online [demo](https://opendatalab.com/OpenSourceTools/Extractor/PDF/) localized deployment version
+- [web_api](./web_api/README.md): Web API Based on FastAPI
+
 

projects/README_zh-CN.md

@@ -5,4 +5,5 @@
 - [llama_index_rag](./llama_index_rag/README_zh-CN.md): 基于 llama_index 构建轻量级 RAG 系统
 - [gradio_app](./gradio_app/README_zh-CN.md): 基于 Gradio 的 Web 应用
 - [web_demo](./web_demo/README_zh-CN.md): MinerU在线[demo](https://opendatalab.com/OpenSourceTools/Extractor/PDF/)本地化部署版本
+- [web_api](./web_api/README.md): 基于 FastAPI 的 Web API