shell: script for decimal to hex converting

Signed-off-by: Fudong Bai <fudongbai@gmail.com>
add prefix to each line

Signed-off-by: Fudong Bai <fudongbai@gmail.com>
add readme file for decimal to hex

Signed-off-by: Fudong Bai <fudongbai@gmail.com>
another script for decimal to hex

Signed-off-by: Fudong Bai <fudongbai@gmail.com>