I have kali installed on my ssd and windows 10 installed on other hdd. 

When I boot from ssd it shows grub menu which only have kali linux option and When I boot from hdd it directly boot windows 10.

So, I want to boot from only ssd, so I can select from grub menu which OS to boot.
(want to add windows 10 option to grub menu)

SOLVED:
I just detected the windows with os-prober and then reconfigured
the grub file by grub-mkconfig. Thanks to Taqras.