Update docs.

Build/MQTTnet.nuspec

@@ -11,16 +11,10 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports v3.1.0, v3.1.1 and v5.0.0 of the MQTT protocol.</description>
     <releaseNotes>
-* [Core] Nuget packages with symbols are now also published to improve debugging.
-* [Core] Improve task handling (thanks to @mwinterb)
-* [ManagedClient] Fix a race condition in the message storage (thanks to @PaulFake).
-* [Server] Added items dictionary to client session in order to share data across interceptors as along as the session exists.
-* [Server] Exposed CONNECT packet properties in Application Message and Subscription interceptor.
-* [Server] Fixed: Sending Large packets with AspnetCore based connection throws System.ArgumentException.
-* [Server] Fixed wrong usage of socket option _NoDelay_.
-* [Server] Added remote certificate validation callback (thanks to @rudacs).
-* [Server] Add support for certificate passwords (thanks to @cslutgen).
-* [MQTTnet.Server] Added REST API for publishing basic messages.
+* [Core] Converted all pending methods to use async/await.
+* [Client] Fixed an issue when checking for revoked SSL certificates (thanks to @cslutgen).
+* [Server] Fixed an issue with empty server certificate passwords (thanks to @SeppPenner).
+* [MQTTnet.Server] Added support for certificate passwords (BREAKING CHANGE IN CONFIG!)
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2019</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags>