[PATCH 09/13] docs/system: Add U2F key to the USB devices examples

[César Belley]

Signed-off-by: César Belley <cesar.belley@lse.epita.fr>
---
 docs/system/usb.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docs/system/usb.rst b/docs/system/usb.rst
index ddfa828d74..9a2f1927c4 100644
--- a/docs/system/usb.rst
+++ b/docs/system/usb.rst
@@ -81,6 +81,9 @@ option or the ``device_add`` monitor command. Available 
devices are:
 ``usb-audio``
    USB audio device
 
+``u2f-{emulated,passthru}``
+   Universal Second Factor device
+
 .. _host_005fusb_005fdevices:
 
 Using host USB devices on a Linux host
-- 
2.28.0