📚 Doc: Update intro.md Static Files section (#3303)

Update intro.md Static Files section

In v3 the apps Static method has been removed and its functionality has been moved to the static middleware.
The given code example has been updated accordingly.

docs/intro.md

@@ -163,7 +163,7 @@ app.Get("/api/*", func(c fiber.Ctx) error {
 
 ### Static Files
 
-To serve static files such as **images**, **CSS**, and **JavaScript** files, use the `Static` method with a directory path. For more information, refer to the [static middleware](./middleware/static.md).
+To serve static files such as **images**, **CSS**, and **JavaScript** files, use the [static middleware](./middleware/static.md).
 
 Use the following code to serve files in a directory named `./public`:
 
@@ -172,12 +172,13 @@ package main
 
 import (
     "github.com/gofiber/fiber/v3"
+    "github.com/gofiber/fiber/v3/middleware/static"
 )
 
 func main() {
     app := fiber.New()
 
-    app.Static("/", "./public")
+    app.Use("/", static.New("./public"))
 
     app.Listen(":3000")
 }