Update bootloader.asm

Removed comments because they're starting to get on my nerves to be honest.
Now,it uses FAT16 instead of FAT12.
Anyway thanks for:
http://wiki.osdev.org/FAT

I used this to understand FAT16 to be able to code it.
The only difference seemed to be the way to jump in the FAT from a cluster to the one following it. :)