Update index.md

Author: Prokopchuk-Valentin

apps/website/docs/factories/index.md

@@ -63,7 +63,7 @@ That's it! Now you can use `@withease/factories` to create and invoke factories
 
 To create a factory you need to call `createFactory` with a factory creator callback:
 
-```js
+```ts
 import { createStore, createEvent, sample } from 'effector';
 import { createFactory } from '@withease/factories';