Samsung Galaxy Note 5 packs a very high resolution display packing nearly twice as many pixels as the Apple iPhone 6S Plus but for some reason, the Korean giant went with five icons in dock. This Note 5 hack will let you add one more icon, bringing total number icons in dock to six.
This will also make the icon size slightly smaller, resulting in 35 dpi icons. Installation is fairly simple and the only thing you will need is TWRP for Galaxy Note 5 which can be downloaded from here. It is also recommended to be on stock Note 5 ROM. Here are the installation instructions:
Perform a Nand Backup or manual backup of touchwiz folder
Flash Via TWRP