updated the link

.github/ISSUE_TEMPLATE/azure_functions_issue.md

@@ -3,4 +3,4 @@ name: Issue with Azure Functions
 about: Need help with Azure Functions
 ---
 
-If you're running the application in Azure Functions, get support [here](TBD).
+If you're running the application in Azure Functions, please file an issue [here](https://github.com/Azure/azure-functions-host/issues/new/choose).