Mention the VS channel change requirement in release-checklist.md (#11268)

* Update release-checklist.md

* Update release checklist for VS build step

Author: JanKrivanek

documentation/release-checklist.md

@@ -96,6 +96,7 @@ if it is not, `darc add-default-channel  --channel "VS {{THIS_RELEASE_VERSION}}"
     - [ ] Respond to the 'VS xyz package stabilization' email - with the merged insertion PR (as nowVS is on stable version).
 - [ ] Update the PackageValidationBaselineVersion to the latest released version ({{THIS_RELEASE_VERSION}}.0) - this might require temporary addition of the [build artifacts feed](https://github.com/dotnet/msbuild/blob/29397b577e3ec0fe0c7650c3ab0400909655dc88/NuGet.config#L9) as the new version is not yet added to the official feeds (this is post release). This can trigger a high severity CG error (https://eng.ms/docs/cloud-ai-platform/devdiv/one-engineering-system-1es/1es-docs/secure-supply-chain/how-to-securely-configure-package-source-files) - however it should be fine to keep this temporary feed untill the release.
 - [ ] Update the requested SDK version for bootstrap folder (the `BootstrapSdkVersion` property in [Versions.props](https://github.com/dotnet/msbuild/blob/main/eng/Versions.props)) if a fresh sdk was released (released runtimes and associated sdk versions can be checked here - https://dotnet.microsoft.com/download/visual-studio-sdks - make sure to always check the details of the appropriate targeted version of .NET for the matching latest version of SDK).
+- [ ] Update `VisualStudio.ChannelName` (and `VisualStudio.MajorVersion` if applicable) of `Windows_NT` build step for our build pipeline in a newly created branch - it should point to the matching VS release branch and make sure the change is not automatically mergable with the interbranch flow (example: #11246): {{URL_OF_PR}}
 
 ## ASAP On/After GA: