Learn Editor: Update provisioned-throughput.md

Author: sydneemayers

articles/ai-services/openai/concepts/provisioned-throughput.md

@@ -35,6 +35,7 @@ An Azure OpenAI Deployment is a unit of management for a specific OpenAI Model.
 | Latency | Max latency constrained from the model. Overall latency is a factor of call shape.  |
 | Utilization | Provisioned-managed Utilization V2 measure provided in Azure Monitor. |
 | Estimating size | Provided calculator in the studio & benchmarking script. |
+| Prompt caching | For supported models, we discount up to 100% of cached input tokens. |
 
 
 ## How much throughput per PTU you get for each model