C#: Analysis change notes

Author: calumgrant

change-notes/1.24/analysis-csharp.md

@@ -13,6 +13,7 @@ The following changes in version 1.24 affect C# analysis in all applications.
 
 | **Query**                    | **Expected impact**    | **Change**                        |
 |------------------------------|------------------------|-----------------------------------|
+| Useless assignment to local variable (`cs/useless-assignment-to-local`) | Fewer false positive results | Results have been removed when the variable is named `_` in a `foreach` statement. | 
 
 ## Removal of old queries