Doc: Incorrect property in example code

The Api code sample is specify to pass an object for the query arguments containing a `_fields` property while the right one is `fields`.

docs/api.md

@@ -38,7 +38,7 @@ const MyComponent (props: Props) => {
                 new Set(['page']),
                 {
                     per_page: 10,
-                    _fields: ['slug', 'title']
+                    fields: ['slug', 'title']
                 }
             )
             .then(setEntities);