Update comment.yml (Azure#11797)

Author: ruowan

.github/comment.yml

@@ -23,3 +23,8 @@
     type: label
     label: Approved-OkToMerge
     onLabeledComments: "Hi @${PRAuthor},Your PR is approved. Congratulations. </br> <li> If your PR is in public repo (azure-rest-api-specs),  PR assignee will merge all updates in the PR shortly afterwards; or pause the PR merge, you need to put on a label <b>DoNotMerge</b> to PR as soon as possible. </li><li>If your PR is in private repo (azure-rest-api-specs-pr),  there won’t be PR merge.  Please refer to this [wiki](https://dev.azure.com/azure-sdk/internal/_wiki/wikis/internal.wiki/205/RP-Scenarios-to-Contribute-to-Swagger?anchor=**public-repository-vs.-private-repository**) for further guidance on how to proceed. </li>"
+
+- rule:
+    type: label
+    label: NewApiVersionRequired
+    onLabeledComments: "<b>NewApiVersionRequired reason:</b></br> </br><b>A service’s API is a contract with customers and is represented by using the api-version query parameter. Changes such as adding an optional property to a request/response or introducing a new operation is a change to the service’s contract and therefore requires a new api-version value. This is critically important for documentation, client libraries, and customer support. </b> </br></br> EXAMPLE: if a customer calls a service in the public cloud using <b>api-version=2020-07-27</b>, the new property or operation may exist but if they call the service in a government cloud, air-gapped cloud, or Azure Stack Hub cloud using the same api-version, the property or operation may not exist. Because there is no clear relationship between the service api-version and the new property/operation, customers can’t trust the documentation and Azure customer have difficulty helping customers diagnose issues. In addition, each client library version documents the service version it supports. When an optional property or new operation is added to a service and its Swagger, new client libraries must be produced to expose this functionality to customers. Without updating the api-version, it is unclear to customers which version of a client library supports these new features.  "