[no ci] [Doc] Fix <ReferenceInput enableGetChoices> example

Author: slax57

docs/ReferenceInput.md

@@ -152,7 +152,7 @@ You can make the `getList()` call lazy by using the `enableGetChoices` prop. Thi
 <ReferenceInput
      source="company_id"
      reference="companies"
-     enableGetChoices={({ q }) => q && q.length >= 2}
+     enableGetChoices={({ q }) => !!(q && q.length >= 2)}
 />
 ```