docs: Add example for composing decorators

This is documentation for changes in
mobxjs#1652

docs/refguide/api.md

@@ -173,6 +173,25 @@ decorate(TodoList, {
 })
 ```
 
+For applying multiple decorators on a single property, you can pass an array of decorators. The decorators application order is from right to left.
+```javascript
+import { decorate, observable } from "mobx"
+import { serializable, primitive } from "serializr"
+import persist from 'mobx-persist';
+
+class Todo {
+    id = Math.random();
+    title = "";
+    finished = false;
+}
+
+decorate(Todo, {
+    title: [serializable(primitive), persist('object'), observable],
+    finished: [serializable(primitive), observable]
+})
+```
+Note: Not all decorators can be composed together, and this functionality is just best-effort. Some decorators affect the instance directly and can 'hide' the effect of other decorators that only change the prototype.
+
 
 ## Computed values