Updated readme with usage instructions

README.md

@@ -3,6 +3,28 @@ demboyz
 
 we dem boyz
 
+### What is it?
+
+Demboyz is a command line tool to convert TF2 STV demos into a human readable json format.
+It supports the following conversions:
+
+    .dem/.json <-> .dem/.json
+    .dem/.json -> .con
+
+    The .dem format is the TF2 STV demo format.
+    The .json format is the demboyz streaming json demo format.
+    The .con format is a log equal to what would be produced by TF2
+    with netmessage/demmessage logs enabled.
+
+### Usage
+
+    ./demboyz mystvdemo.dem mystvdemo.json
+    ./demboyz mystvdemo.dem mystvdemo.con
+    ./demboyz mystvdemo.json mystvdemo.dem
+    ./demboyz mystvdemo.json mystvdemo.con
+
+In the first example, mystvdemo.dem will be read from the current working directory, while mystvdemo.json will be written to the current working directory.
+
 
 ### Using Vagrant