Replace Qemu by QEMU in user visible documentation

The official spelling is QEMU.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 83b2ad5..d18dff0 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -968,7 +968,7 @@
 
 QEMU emulates a PCI UHCI USB controller. You can virtually plug
 virtual USB devices or real host USB devices (experimental, works only
-on Linux hosts).  Qemu will automatically create and connect virtual USB hubs
+on Linux hosts).  QEMU will automatically create and connect virtual USB hubs
 as necessary to connect multiple USB devices.
 
 @menu