Typo "a [Azure free account]"→"an [Azure free account]"

https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/upgrade-azure-subscription
https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/cost-management-billing/manage/upgrade-azure-subscription.md
#PingMSFTDocs

Author: hyoshioka0128

articles/cost-management-billing/manage/upgrade-azure-subscription.md

@@ -16,7 +16,7 @@ ms.author: banders
 
 You can upgrade your [Azure free account](https://azure.microsoft.com/free/) to [pay-as-you-go rates](https://azure.microsoft.com/offers/ms-azr-0003p/) in the Azure portal.
 
-If you have an [Azure for Students Starter account](https://azure.microsoft.com/offers/ms-azr-0144p/) and are eligible for an [Azure free account](https://azure.microsoft.com/free/), you can upgrade to it to a [Azure free account](https://azure.microsoft.com/free/). You get $200 Azure credit in your billing currency and 12 months of free services on upgrade. If you don't qualify for a free account, you can upgrade to [pay-as-you-go rates](https://azure.microsoft.com/offers/ms-azr-0003p/) with a [support request](https://go.microsoft.com/fwlink/?linkid=2083458).
+If you have an [Azure for Students Starter account](https://azure.microsoft.com/offers/ms-azr-0144p/) and are eligible for an [Azure free account](https://azure.microsoft.com/free/), you can upgrade to it to an [Azure free account](https://azure.microsoft.com/free/). You get $200 Azure credit in your billing currency and 12 months of free services on upgrade. If you don't qualify for a free account, you can upgrade to [pay-as-you-go rates](https://azure.microsoft.com/offers/ms-azr-0003p/) with a [support request](https://go.microsoft.com/fwlink/?linkid=2083458).
 
 If you have an [Azure for Students](https://azure.microsoft.com/offers/ms-azr-0170p/) account, you can upgrade to [pay-as-you-go rates](https://azure.microsoft.com/offers/ms-azr-0003p/).