fix: live-server set port use [--port=PORT] (#5687)

Author: ijackwu

docs/src/guide/essentials/build.md

@@ -47,7 +47,7 @@ cd apps/web-antd/dist
 # 本地预览，默认端口8080
 live-server
 # 指定端口
-live-server --port 9000
+live-server --port=9000
 ```
 
 ## 压缩