How to install OTA updates after Unlock/Root/TWRP Bootloader?

I unlocked and rooted my Nexus 5X and installed the TRWP bootloader according to Heisenberg's great instructions.

But now I'm getting OTA updates downloaded to the phone. How do I install them? Or probably a more correct question, does anyone know where I can find those updates in a TWRP flashable format? I can't find them.

Thanks,
Tom