C#: Add change note for datetime queries.

Author: calumgrant

change-notes/1.23/analysis-csharp.md

@@ -2,6 +2,15 @@
 
 The following changes in version 1.23 affect C# analysis in all applications.
 
+## New queries
+
+## New queries
+
+| **Query**                   | **Tags**  | **Purpose**                                                        |
+|-----------------------------|-----------|--------------------------------------------------------------------|
+| Unsafe year argument for 'DateTime' constructor (`cs/unsafe-year-construction`) | reliability, date-time | Finds incorrect manipulation of `DateTime` values, which could lead to invalid dates. |
+| Mishandling the Japanese era start date (`cs/mishandling-japanese-era`) | reliability, date-time | Finds hard-coded Japanese era start dates that could be invalid. |
+
 ## Changes to existing queries
 
 | **Query**                    | **Expected impact**    | **Change**                        |