docs: add export const dynamic = 'force-static' to Route Handlers example on Static Exports

Author: m-kawafuji

docs/01-app/02-guides/static-exports.mdx

@@ -232,15 +232,19 @@ export default function Page() {
 
 ### Route Handlers
 
-Route Handlers will render a static response when running `next build`. Only the `GET` HTTP verb is supported. This can be used to generate static HTML, JSON, TXT, or other files from cached or uncached data. For example:
+Route Handlers will render a static response when running `next build`. Only the `GET` HTTP verb is supported. This can be used to generate static HTML, JSON, TXT, or other files from cached or uncached data. Since Route Handlers are dynamic by default, you must explicitly mark the handler as static by adding `export const dynamic = 'force-static'` when a static export is enabled. For example:
 
 ```ts filename="app/data.json/route.ts" switcher
+export const dynamic = 'force-static'
+
 export async function GET() {
   return Response.json({ name: 'Lee' })
 }
 ```
 
 ```js filename="app/data.json/route.js" switcher
+export const dynamic = 'force-static'
+
 export async function GET() {
   return Response.json({ name: 'Lee' })
 }