Enable syntax highlighting/linting for scriptlets

Various editors depend on the shebang line to determine what language
to use for syntax highlighting and/or linting.  Therefore add one.  It
is ignored when sourcing and the scriplets are not executable so the
shebang will never be used.

Signed-off-by: Daniel F. Dickinson <[email protected]>

stage2/EXPORT_IMAGE

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 IMG_SUFFIX="-lite"
 if [ "${USE_QEMU}" = "1" ]; then
 	export IMG_SUFFIX="${IMG_SUFFIX}-qemu"

stage2/EXPORT_NOOBS

@@ -1,2 +1,5 @@
+#!/bin/bash
+
+# shellcheck disable=SC2034
 NOOBS_NAME="Raspbian Lite"
 NOOBS_DESCRIPTION="A port of Debian with no desktop environment"