update README

Author: hansfbaier

README.md

@@ -3,4 +3,9 @@
 DECA based USB 2.0 High Speed audio interface
 
 ## Status / current limitations
-* in development, not working
+* enumerates as class compliant audio device on Linux and Windows.
+* Works on the FPGA, DAC chip output sound
+* only 48kHz sample rate supported
+* audio input is still a dummy. The ADC still needs to be hooked up,
+  and an I2S receiver core is missing
+* integrated USB2 high speed logic analyzer works