Documented the supported and unsupported features

Author: njh

README.md

@@ -1,10 +1,32 @@
 Command line tools written in C for the MQTT-S (MQTT For Sensor Networks) protocol.
 
+Supported Features
+------------------
+
+- QoS 0
+- Keep alive pings
+- Publishing retained messages
+- Publishing empty messages
+- Subscribing to named topic
+- Clean / unclean sessions
+- Manual and automatic client ID generation
+
+
+Unsupported Features
+--------------------
+
+- QoS -1, 1 and 2
+- Last Will and Testament
+- Displaying topic name with each recieved message (aka verbose mode)
+- Packets longer than 255 bytes
+- Automatic gateway discovery
+- Pre-defined topic IDs and short topic names
+
 
 Building
 --------
 
-Just run 'make'.
+Just run 'make' on a POSIX system.
 
 
 Publishing