Call out dotnet-test-cloud.ps1 script

Author: AArnott

CONTRIBUTING.md

@@ -39,7 +39,11 @@ This repository can be built on Windows, Linux, and OSX.
 
 Building, testing, and packing this repository can be done by using the standard dotnet CLI commands (e.g. `dotnet build`, `dotnet test`, `dotnet pack`, etc.).
 
-[pwsh]: https://learn.microsoft.com/powershell/scripting/install/installing-powershell
+## Testing
+
+You can use `dotnet test` to build and/or test the repo.
+
+There may be tests that are known to be unstable or have special requirements. These can be avoided by running tests using the [dotnet-test-cloud.ps1](tools/dotnet-test-cloud.ps1) script *after* running `dotnet build`.
 
 ## Releases
 
@@ -96,3 +100,5 @@ git checkout origin/main
 # resolve any conflicts, then commit the merge commit.
 git push origin -u HEAD
 ```
+
+[pwsh]: https://learn.microsoft.com/powershell/scripting/install/installing-powershell