docs: reintroduce import/require usage for user-event

Author: nickserv

Diff for: docs/user-event/install.mdx

@@ -26,6 +26,16 @@ yarn add --dev @testing-library/user-event
 </TabItem>
 </Tabs>
 
+Now simply import it in your tests:
+
+```js
+import userEvent from '@testing-library/user-event'
+
+// or
+
+const {default: userEvent} = require('@testing-library/user-event')
+```
+
 Note that `@testing-library/user-event` requires `@testing-library/dom`.
 
 If you use one of the