typo in BarcodeScanningProcessor (firebase#495)

Missed letter F in FirebaseVisionBarcode in comment

mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/barcodescanning/BarcodeScanningProcessor.java

@@ -39,7 +39,7 @@ public BarcodeScanningProcessor() {
     // Note that if you know which format of barcode your app is dealing with, detection will be
     // faster to specify the supported barcode formats one by one, e.g.
     // new FirebaseVisionBarcodeDetectorOptions.Builder()
-    //     .setBarcodeFormats(irebaseVisionBarcode.FORMAT_QR_CODE)
+    //     .setBarcodeFormats(FirebaseVisionBarcode.FORMAT_QR_CODE)
     //     .build();
     detector = FirebaseVision.getInstance().getVisionBarcodeDetector();
   }