bootmanager: add SPDX identifiers

bootmanager/add_to_system_reboot.sh

@@ -1,4 +1,5 @@
-#! /bin/bash
+#! /bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
 [ -z "$TARGET_BRANDING" ] && printf "TARGET_BRANDING value is not set.\a\n" 1>&2 && exit 1
 
 TargetDir="${TARGET_DIR:+$TARGET_DIR/}"

bootmanager/bootmanager

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
 #
 # Boot Manager for AVM FRITZ!Box 7490
 #

bootmanager/gui_bootmanager

@@ -1,5 +1,6 @@
 #! /bin/sh
 # vim: set tabstop=4 syntax=sh :
+# SPDX-License-Identifier: GPL-2.0-or-later
 #######################################################################################################
 #                                                                                                     #
 # extension for the 'restart' page of AVM's FRITZ!OS GUI (reboot.lua) to provide a selection between  #