Update what-is-ai-foundry.md

from MicrosoftDocs/azure-ai-docs-pr#3094

Author: sdgilley

articles/ai-foundry/what-is-ai-foundry.md

@@ -82,7 +82,7 @@ You can [explore Azure AI Foundry portal (including the model catalog)](./how-to
 
 But for full functionality there are some requirements:
 
-- You need an [Azure account](https://azure.microsoft.com/free/). 
+You need an [Azure account](https://azure.microsoft.com/pricing/purchase-options/azure-account). 
 
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