Update documentation

Build/MQTTnet.nuspec

@@ -12,6 +12,7 @@
     <description>MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
     <releaseNotes>* [Client] Added support for web socket communication channel (thanks to nowakpiotr)
 * [Core] Huge performance optimizations (thanks to JanEggers)
+* [Client] Fixed an issue when calling _DisconnectAsync_ and the connection is already closed.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2017</copyright>
     <tags>MQTT MQTTClient MQTTServer MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Queue Hardware Arduino</tags> 

README.md

@@ -11,15 +11,17 @@ MQTTnet is a .NET library for MQTT based communication. It provides a MQTT clien
 # Features
 
 ### General
-* Performance optimized (publishing ~18.000 messages per second on local machine)
 * Async support
 * TLS 1.2 support for client and server (but not UWP servers)
 * Extensible communication channels (i.e. In-Memory, TCP, TCP+TLS, WS)
-* Interfaces included for mocking and testing
+* Performance optimized (processing ~20.000 messages / second)*
 * Lightweight (only the low level implementation of MQTT, no overhead)
+* Interfaces included for mocking and testing
 * Access to internal trace messages
 * Unit tested (55+ tests)
 
+\* Tested on local machine with MQTTnet client and server running in the same process.
+
 ### Client
 * Rx support (via another project)
 * Communication via TCP (+TLS) or WS (WebSocket)