Update README with Detailed WebUI Service Launch Instructions (#694)

### What problem does this PR solve?

Improve README by detailing Launch Service from Source section

This commit enhances the README document by adding comprehensive steps
for running the WebUI service in the 'Launch Service from Source'
section. It aims to provide clearer guidance for users attempting to
start the service from the source code, making the setup process more
accessible and understandable.

Key changes include:
- Detailed instructions for setting up and running the WebUI service.
- Necessary prerequisites for launching the service from source.

This update ensures that users have all the information they need to
successfully launch the service, improving the overall usability of our
project.

### Type of change

- [x] Documentation Update

README.md

@@ -249,6 +249,29 @@ $ chmod +x ./entrypoint.sh
 $ bash ./entrypoint.sh
 ```
 
+7. Start the WebUI service
+```bash
+$ cd web
+$ npm install --registry=https://registry.npmmirror.com --force
+$ vim .umirc.ts
+# Modify proxy.target to 127.0.0.1:9380
+$ npm run dev 
+```
+
+8. Deploy the WebUI service
+```bash
+$ cd web
+$ npm install --registry=https://registry.npmmirror.com --force
+$ umi build
+$ mkdir -p /ragflow/web
+$ cp -r dist /ragflow/web
+$ apt install nginx -y
+$ cp ../docker/nginx/proxy.conf /etc/nginx
+$ cp ../docker/nginx/nginx.conf /etc/nginx
+$ cp ../docker/nginx/ragflow.conf /etc/nginx/conf.d
+$ systemctl start nginx
+```
+
 ## 📚 Documentation
 
 - [FAQ](./docs/faq.md)

README_zh.md

@@ -247,7 +247,28 @@ $ docker compose -f docker-compose-base.yml up -d
 $ chmod +x ./entrypoint.sh
 $ bash ./entrypoint.sh
 ```
+7. 启动WebUI服务
+```bash
+$ cd web
+$ npm install --registry=https://registry.npmmirror.com --force
+$ vim .umirc.ts
+# 修改proxy.target为127.0.0.1:9380
+$ npm run dev 
+```
 
+8. 部署WebUI服务
+```bash
+$ cd web
+$ npm install --registry=https://registry.npmmirror.com --force
+$ umi build
+$ mkdir -p /ragflow/web
+$ cp -r dist /ragflow/web
+$ apt install nginx -y
+$ cp ../docker/nginx/proxy.conf /etc/nginx
+$ cp ../docker/nginx/nginx.conf /etc/nginx
+$ cp ../docker/nginx/ragflow.conf /etc/nginx/conf.d
+$ systemctl start nginx
+```
 ## 📚 技术文档
 
 - [FAQ](./docs/faq.md)