2.2.0 release notes should mention breaking change -- $ is no longer a legal character in collection names

We discovered that we made a breaking change in 2.2.0 but hadn't documented it. Version 2.0.x would let you create and use a collection with "$" (dollar sign) in its name. In version 2.2.0, User Assertion 15937 – "invalid collection name: " + target – is thrown if the collection name contains a "$".

It would be good to add this to the release notes for 2.2.0.