Prepare for release (Azure#16838)

Author: JoshLove-msft

sdk/eventgrid/Azure.Messaging.EventGrid/CHANGELOG.md

@@ -1,11 +1,13 @@
 # Release History
-## 4.0.0-beta.4 (Unreleased)
+## 4.0.0-beta.4 (2020-11-10)
 
+### Fixed
+- Fixed bug where missing required properties on CloudEvent would cause deserialization to fail.
 
 ## 4.0.0-beta.3 (2020-10-06)
 
 ### Fixed
-- Fix bug where we were not parsing the Topic when parsing into EventGridEvents.
+- Fixed bug where we were not parsing the Topic when parsing into EventGridEvents.
 
 ### Added
 

sdk/eventgrid/Azure.Messaging.EventGrid/README.md

@@ -16,7 +16,7 @@ Use the client library for Azure Event Grid to:
 Install the client library from [NuGet](https://www.nuget.org/):
 
 ```PowerShell
-dotnet add package Azure.Messaging.EventGrid --version 4.0.0-beta.1
+dotnet add package Azure.Messaging.EventGrid --version 4.0.0-beta.4
 ```
 
 ### Prerequisites