usb notes update

README.md

@@ -113,7 +113,7 @@ New files include:
 * [meta-ezynq](https://sourceforge.net/p/elphel/meta-ezynq) - recipes for Yocto Poky
 
 ## Known issues
-1. [works with u-boot-xlnx 'master'-branch] USB does not work yet.
+1. [FIXED] USB does not work yet.
 2. [FIXED] Ethernet is not tested (on the board we have it does not work with provided images, so we
    suspect a hardware problem.
 3. Bitstream loading is not tested, current code does not enable level shifters - it may be