Update docs.

Build/MQTTnet.nuspec

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     <requireLicenseAcceptance>true</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] Improved logger performance (BREAKING CHANGE!).
-* [Core] Renamed some topic filter relevant classes (BREAKING CHANGE!).
-* [Core] Improved task management for UWP connections (thanks to @xgstation).
-* [Core] Fixed broken logger which decreases overall performance.
-* [Core] Fixed issue in closed socket detection (fixes high CPU load issue).
-* [Client] Added method to trigger PING/PONG manually (connection check etc.).
-* [Client] Added support for certificate validation callback when using Web Sockets (requires netstandard2.1+).
-* [Client] Fixed a memory leak when web socket based connections trying to reconnect with an offline server.
-* [Client] Fixed a memory leak when TCP based connections trying to reconnect with an offline server.
-* [Client] Fixed an issue when connecting to an invalid host (format).
-* [Client] Added support for user properties in CONNECT packet.
-* [Client] Removed _KeepAliveSendInterval_ and improved keep alive handling (BREAKING CHANGE!).
-* [ManagedClient] Added method to trigger PING/PONG manually (connection check etc.).
-* [MQTTnet.AspNetCore] improved compatibility with AspNetCore 3.1.
-* [MQTTnet.AspNetCore] Fixed several packaging issues with the Nuget package.
-* [MQTTnet.Server] Fixed wrong version output.
+* [Client] Fixed issue in keep alive handling.
+* [MQTTnet.Server] Added support for delivering static files (HTML, JavaScript etc.).
+* [MQTTnet.Server] Fixed web socket protocol errors (when using paho JS etc.).
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2020</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>