Update models.md

Author: LHL407

articles/ai-foundry/openai/includes/retirement/models.md

@@ -87,7 +87,7 @@ We notify all customers with these preview deployments at least 30 days before t
 
 Fine-tuned models retire in two phases: *training* and *deployment*.
 
-All fine-tuned models follow their equivalent base model for *training* retirement. Once retired, a given model is no longer available for fine tuning.
+All fine-tuned models follow their equivalent base model for *training* retirement. After a model is retired, it's is no longer available for fine-tuning.
 
 For fine-tuned models made generally available since `gpt-4o-2024-08-06`, *deployment* retirement occurs 1 year after *training* retirement. At deployment retirement, inference and deployment return error responses.