armvirt: README: rename it from LEDE to OpenWrt

Signed-off-by: Josef Schlehofer <[email protected]>

target/linux/armvirt/README

@@ -1,4 +1,4 @@
-This is intended to be used with LEDE project to provide image for use with
+This is intended to be used with OpenWrt project to provide image for use with
 QEMU ARM virt machine.
 
 Run with qemu-system-arm