Update link to Azure API guidelines within Operation.md (#6221)

doc/Operation.md

@@ -1,6 +1,6 @@
 # Operation\<T>
 
-The Azure SDK for C++ defines an Operation as an abstract class to support a long running operation ([LRO](https://github.com/microsoft/api-guidelines/blob/vNext/Guidelines.md#13-long-running-operations)).
+The Azure SDK for C++ defines an Operation as an abstract class to support a long running operation ([LRO](https://github.com/microsoft/api-guidelines/blob/vNext/azure/Guidelines.md#long-running-operations--jobs)).
 
 The SDK clients would define a concrete class from the `Operation<T>` which an end users can consume for getting the status of the running operation.