Merge branch 'pr/3497' into devel

Fixes #3497.

packages/reactive-dict/README.md

@@ -5,12 +5,14 @@ datatype for use with
 [tracker](https://atmospherejs.com/meteor/tracker). It provides all of
 the functionality of the `Session` object documented in the [main
 Meteor docs](https://docs.meteor.com/#session), such as reactive
-`get`, `set`, and `equals` functions, except that its contents are not
-saved across Hot Code Push client code updates.
+`get`, `set`, and `equals` functions.
+
+If you provide a name to its constructor, its contents will be saved across Hot
+Code Push client code updates.
 
 Example usage:
 ```
-> var dict = new ReactiveDict;
+> var dict = new ReactiveDict('myDict');
 > dict.set("weather", "cloudy");
 > Tracker.autorun(function () { console.log("now " + dict.get("weather")); });
 now cloudy