Learn Editor: Update prompt-caching.md

Author: sydneemayers

articles/ai-services/openai/how-to/prompt-caching.md

@@ -83,4 +83,8 @@ To improve the likelihood of cache hits occurring, you should structure your req
 
 ## Can I disable prompt caching?
 
-Prompt caching is enabled by default. There is no opt-out option.
+Prompt caching is enabled by default. There is no opt-out option.
+
+## How does prompt caching work for Provisioned deployments?
+
+For supported models on provisioned deployments, we discount up to 100% of cached input tokens. For more information, see our [Provisioned Throughput documentation](https://learn.microsoft.com/en-us/azure/ai-services/openai/concepts/provisioned-throughput).