C#: Add change note

Author: hvitved

change-notes/1.26/analysis-csharp.md

@@ -21,6 +21,10 @@ The following changes in version 1.26 affect C# analysis in all applications.
 * Partial method bodies are extracted. Previously, partial method bodies were skipped completely.
 * Inferring the lengths of implicitely sized arrays is fixed. Previously, multidimensional arrays were always extracted with the same length for
 each dimension. With the fix, the array sizes `2` and `1` are extracted for `new int[,]{{1},{2}}`. Previously `2` and `2` were extracted.
+* The extractor is now assembly-insensitive by default. This means that two entities with the same
+  fully-qualified name are now mapped to the same entity in the resulting database, regardless of
+  whether they belong to different assemblies. Assembly sensitivity can be reenabled by passing
+  `--assemblysensitivetrap` to the extractor.
 
 ## Changes to libraries