Update documentation

MQTTnet.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>MQTTnet</id>
-    <version>2.1.2.0</version>
+    <version>2.1.3.0</version>
     <authors>Christian Kratky</authors>
     <owners>Christian Kratky</owners>
     <licenseUrl>https://github.com/chkr1011/MQTTnet/blob/master/LICENSE</licenseUrl>
@@ -10,11 +10,8 @@
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
-    <releaseNotes>* [Server] Added support for complex client IDs.
-      * [Server] Fixed an issue with not correctly removed old client sessions.
-      * [Server] Several minor performance improvements.
-      * [Server] An existing client session is no longer closed if a new client connection is invalid.
-      * [Client] Added support for sending "CleanSession" flag.</releaseNotes>
+    <releaseNotes>* [Core] Any exception while accessing the underlying data source is now rethrown as "MqttCommunicationException".
+* [Core] Extended exception information when an invalid packet type is received.</releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2017</copyright>
     <tags>MQTT MQTTClient MQTTServer MQTTBroker Broker</tags>
   </metadata>

README.md

@@ -2,6 +2,8 @@
 <img src="https://github.com/chkr1011/MQTTnet/blob/master/Images/Logo_128x128.png?raw=true" width="128">
 </p>
 
+[![Build Status](https://img.shields.io/nuget/v/MQTTnet.svg)](https://www.nuget.org/packages/MQTTnet/)
+
 # MQTTnet
 MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server. The implementation is based on the documentation from http://mqtt.org/.