Forgot to add domains to property types.

Adding-new-objects.md

@@ -65,6 +65,7 @@ So to create a new object, choose one of the two to extend, and then create a cl
     - Property type can be:
         - static types: `"string", "number", "boolean"`
         - Expressions: `"Expression"`
+        - Domains and ranges: `"Domain"`
         - Enumerations: `new P.Enum("value 1", "value 2"...)` displayed as comboboxes, property is set as the string value of the enum.
         - Lists: `new P.List(<static type>, format = /^.+$/, label = '', forbidAdding = false)`
         - Dictionaries: `new P.Dictionary(valueType: <static type>, keytType: <static type>, format = /^.+$/, preKeyLabel = '', postKeyLabel = ': ', forbidAdding = false)`