Update accessor demo_app instructions for install

Missing the 'apex' directory in the path in out/target

Test: copy/paste commands && verify
Bug: none
Change-Id: Ib38c5f4ec29cb5d002831f13d5722a229a03ac76
diff --git a/demo_accessor/README.md b/demo_accessor/README.md
index a3959a5..c85cf3c 100644
--- a/demo_accessor/README.md
+++ b/demo_accessor/README.md
@@ -28,7 +28,7 @@
 ```shell
 adb remount -R || adb wait-for-device  # Remount to push apex to /system_ext
 adb root && adb remount                # Ensure it's rebooted.
-adb push $ANDROID_PRODUCT_OUT/system_ext/com.android.virt.accessor_demo.apex /system_ext/apex
+adb push $ANDROID_PRODUCT_OUT/system_ext/apex/com.android.virt.accessor_demo.apex /system_ext/apex
 adb reboot && adb wait-for-device      # Ensure that newly pushed apex at /system_ext is installed
 ```