update batch scripts to further check filename.

bin/device-update.sh

@@ -12,6 +12,7 @@ Flash image file to device, leave existing system intact."
     -p ESPTOOL_PORT  Set the environment variable for ESPTOOL_PORT.  If not set, ESPTOOL iterates all ports (Dangerrous).
     -P PYTHON        Specify alternate python interpreter to use to invoke esptool. (Default: "$PYTHON")
     -f FILENAME      The *update.bin file to flash.  Custom to your device type.
+    
 EOF
 }
 
@@ -42,12 +43,12 @@ shift "$((OPTIND-1))"
     shift
 }
 
-if [ -f "${FILENAME}" ]; then
-	echo "Trying to flash update ${FILENAME}."
+if [ -f "${FILENAME}" ] && [ $FILENAME == *"update"* ]; then
+	printf "Trying to flash update ${FILENAME}"
 	$PYTHON -m esptool --baud 115200 write_flash 0x10000 ${FILENAME}
 else
-	echo "Invalid file: ${FILENAME}"
 	show_help
+	echo "Invalid file: ${FILENAME}"
 fi
 
 exit 0