docs: Update PluginIdfa instance

Author: Rohithgilla12

Diff for: packages/plugins/plugin_idfa/README.md

@@ -24,7 +24,7 @@ You also need to ensure you have a description for `NSUserTrackingUsageDescripti
 
 Follow the [instructions for adding plugins](https://github.com/segmentio/analytics_flutter_#adding-plugins) on the main Analytics client:
 
-In your code where you initialize the analytics client call the `.add(plugin)` method with an `AppsFlyerDestination` instance. 
+In your code where you initialize the analytics client call the `.add(plugin)` method with an `PluginIdfa` instance. 
 
 ```dart
 import 'package:analytics/client.dart';
@@ -108,4 +108,4 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
-```
+```