Update docs.

Build/MQTTnet.NETStandard.nuspec

@@ -9,7 +9,7 @@
     <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <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). This package contains the .NET Standard version of the library only.</description>
+    <description>This package contains the .NET Standard version of MQTTnet only.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</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> 

Build/MQTTnet.nuspec

@@ -9,7 +9,7 @@
     <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <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).</description>
+    <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] Fixed issues in MQTTv5 message encoding and decoding.
 * [Core] Added extension method to allow usage of _WebSocket4Net_ in clients to fix issues with AWS and Xamarin.
@@ -23,7 +23,9 @@
 * [Server] Exposed _ClientCertificateRequired_ and _CheckCertificateRevocation_ at TLS options.
 * [Server] Exposed client certificate at client connection validator.
 * [Server] The subscription interceptor now supports altering the entire topic filter.
+* [Server] Exposed more properties to the connection validator context.
 * [MQTTnet.Server] Added authentication support via Python script file.
+* [MQTTnet.Server] Migrated the result of connection validations to _ReasonCode_ (MQTTv5) instead of _ReturnCode_ (MQTTv3 only).
     </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>