Update Transpiler

Transpiler.md

@@ -29,6 +29,11 @@ Features
 - string: `Length` to `length()` 
 - Automatic string conversion of number/string add binary expressions `n+s` to `str(n)+s`
 
+### **C# Delegates/GDScript Callable**
+- rewrite to not-nullable type
+- null-initializers from `null` to `Callable()`
+- null-comparisons from `c == null` to `c == null || c.is_null()`
+
 ### **Math**
 - float.MaxValue converted to value
 - `float.IsInfinity` to `is_inf`