meta-skeleton: rename busybox's bbappend file

As busybox has been upgraded, rename this bbappend file to make it
match the current version of busybox.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>

diff --git a/meta-skeleton/recipes-core/busybox/busybox_1.21.1.bbappend b/meta-skeleton/recipes-core/busybox/busybox_%.bbappend
similarity index 100%
rename from meta-skeleton/recipes-core/busybox/busybox_1.21.1.bbappend
rename to meta-skeleton/recipes-core/busybox/busybox_%.bbappend