Issue #308 Accounting Docs Type fix

Author: pumpkinball

docs/v2/accounting/index.html

@@ -11292,7 +11292,7 @@ <h3>Usage and SDK Samples</h3>
 $lineItem->setQuantity(1.0);
 $lineItem->setUnitAmount(20.0);
 $lineItem->setAccountCode('000');
-$lineItem->setTracking(lineItemTrackings);
+$lineItem->setTracking($lineItemTrackings);
 $lineItems = [];
 array_push($lineItems, $lineItem);