Fix the prerender cache update error with the example Dockerfile (#54870

)

It seems the app router attempts to write its cache to both `.next/cache` and `.next/server` in docker.

This fix should fix standalone output server's error `Failed to update prerender cache... [Error: EACCES: permission denied...` when deployed in a docker container with the example Dockerfile.

Related discussion: #51164

examples/with-docker/Dockerfile

@@ -45,6 +45,10 @@ RUN adduser --system --uid 1001 nextjs
 
 COPY --from=builder /app/public ./public
 
+# Set the correct permission for prerender cache
+RUN mkdir .next
+RUN chown nextjs:nodejs .next
+
 # Automatically leverage output traces to reduce image size
 # https://nextjs.org/docs/advanced-features/output-file-tracing
 COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./