icE1usb fw: Minor doc string update

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: If0b37021698b2d17b8412a1c05a9c7101b06a506
diff --git a/firmware/ice40-riscv/icE1usb/ice1usb_proto.h b/firmware/ice40-riscv/icE1usb/ice1usb_proto.h
index 38cb23b..5b65d76 100644
--- a/firmware/ice40-riscv/icE1usb/ice1usb_proto.h
+++ b/firmware/ice40-riscv/icE1usb/ice1usb_proto.h
@@ -16,6 +16,8 @@
 
 /*! returns a bit-mask of optional device capabilities (see enum e1usb_dev_capability) */
 #define ICE1USB_DEV_GET_CAPABILITIES	0x01
+
+/*! returns a string describing the firmware version */
 #define ICE1USB_DEV_GET_FW_BUILD	0x02
 
 enum e1usb_dev_capability {