C#: add change note

Author: Jami Cogswell

csharp/ql/lib/change-notes/2023-05-17-update-csharp-sink-kinds.md

@@ -0,0 +1,9 @@
+---
+category: minorAnalysis
+---
+* Updated the following C# sink kind names. Any custom data extensions that use these sink kinds will need to be updated accordingly in order to continue working.
+  * `code` to `code-injection`
+  * `sql` to `sql-injection`
+  * `html` to `html-injection`
+  * `xss` to `js-injection`
+  * `remote` to `file-content-store`