added changeset for class diagram

.changeset/polite-rules-rescue.md

@@ -0,0 +1,15 @@
+---
+'mermaid': minor
+---
+
+Class diagram changes:
+
+- Updates the class diagram to the new unified way of rendering.
+- Includes a new "classBox" shape to be used in diagrams
+- Other updates such as:
+  - the option to hide the empty members box in class diagrams,
+  - support for handDrawn look,
+  - the introduction of the classDef statement into class diagrams,
+  - support for styling the default class,
+  - support lollipop interfaces.
+- Includes fixes / additions for #5562 #3139 and #4037