qemu-options.hx: describe hub chardev and aggregation of several backends

This adds a few lines describing `hub` aggregator configuration
for aggregation of several backend devices with a single frontend
device.

Signed-off-by: Roman Penyaev <r.peniaev@gmail.com>
Reviewed-by: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: qemu-devel@nongnu.org
Message-ID: <20250123085327.965501-5-r.peniaev@gmail.com>
1 file changed