Update Transpiler

Transpiler.md

@@ -39,6 +39,9 @@ Features
 - variable null-initializers from `null` to `Callable()`
 - null-comparisons from `c == null` to `c == null || c.is_null()`
 
+### **Nullables**
+- Shim null assignment converting `null` to `RJ_GDGlue.return_null()`
+
 ### **Math**
 - float.MaxValue converted to value
 - `float.IsInfinity` to `is_inf`