Grub bootloader generally has other OSs on the device in it. 
But the latest grub version removed that option by default. We should enable it ourself. 

nano /etc/default/grub
add GRUB_DISABLE_OS_PROBER=false.
edit the default with the number for os starting from 0 for kali
change timeout
then ^O and enter
then ^X to exit
finally type update-grub