Update documentation for Order#getAppliedRuleIds

Update the documentation for getAppliedRuleIds, as it is not immediately clear if this is a single number in a string, or several that are comma separated.

Author: zack6849

app/code/Magento/Sales/Api/Data/OrderInterface.php

@@ -580,6 +580,7 @@ public function getAdjustmentPositive();
 
     /**
      * Gets the applied rule IDs for the order.
+     * Rules are comma separated if there are more than one.
      *
      * @return string|null Applied rule IDs.
      */

app/code/Magento/Sales/Api/Data/OrderItemInterface.php

@@ -414,6 +414,7 @@ public function getAmountRefunded();
 
     /**
      * Gets the applied rule IDs for the order item.
+     * Rules are comma separated if there are more than one.
      *
      * @return string|null Applied rule IDs.
      */

app/code/Magento/Sales/Model/Order.php

@@ -2112,6 +2112,7 @@ public function getAdjustmentPositive()
 
     /**
      * Returns applied_rule_ids
+     * Rules are comma separated if there are more than one.
      *
      * @return string|null
      */

app/code/Magento/Sales/Model/Order/Item.php

@@ -724,6 +724,7 @@ public function getAmountRefunded()
 
     /**
      * Returns applied_rule_ids
+     * Rules are comma separated if there are more than one.
      *
      * @return string|null
      */