Update prompt_flow.md

Author: Roopan-Microsoft

docs/prompt_flow.md

@@ -45,7 +45,7 @@ This is a known issue and can be resolved by initiating a compute session. Once
 
 Follow these steps to update the flow:
 
-1. Navigate to the flow in Azure Machine Learning Studio and make the necessary changes
+1. Navigate to the flow in Azure Machine Learning Studio and make the necessary changes.
 1. Download the updated flow files to the [../infra/prompt-flow/cwyd/](../infra/prompt-flow/cwyd/) directory by clicking the download button in the Files tab
 ![Download](images/prompt-flow-download.png)
 1. Replace the content of `flow.dag.template.yaml` with your new flow from the `flow.dag.yaml` file