Update README.md - add `--rwdir /tmp` in weston instruction

README.md

@@ -31,7 +31,7 @@ This following command will launch virtme with a display, keeping the serial in
 
 ```
 # NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
-$(host) virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+$(host) virtme-run --graphics --rwdir /tmp --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
 ```
 
 Where $KDIR is the path of your kernel directory.