This is not a main-line, WHQL driver. This is not even a mainstream beta driver. The beta GeForce 364.91 drivers (364.16 on Linux) are only available on the NVIDIA developer website, which, yes, is publicly accessible, but should probably not be installed unless you are intending to write software and every day counts. Also, some who have installed it claim that certain Vulkan demos stop working. I'm not sure whether that means the demo is out-of-date due to a rare conformance ambiguity, the driver has bugs, or the reports themselves are simply unreliable.
That said, if you are a software developer, and you don't mind rolling back if things go awry, you can check out the new version at NVIDIA's website. It updates Vulkan to 1.0.8, which is just documentation bugs and conformance tweaks. These things happen over time. In fact, the initial Vulkan release was actually Vulkan 1.0.3, if I remember correctly.
The driver also addresses issues with Vulkan and NVIDIA Optimus technologies, which is interesting. Optimus controls which GPU acts as primary in a laptop, switching between the discrete NVIDIA one and the Intel integrated one, depending on load and power. Vulkan and DirectX 12, however, expose all GPUs to the system. I'm curious how NVIDIA knows whether to sleep one or the other, and what that would look like to software that enumerates all compatible devices. Would it omit listing one of the GPUs? Or would it allow the software to wake the system out of Optimus should it want more performance?
Anywho, the driver is available now, but you probably should wait for official releases. The interesting thing is this seems to mean that NVIDIA will continue to release non-public Vulkan drivers. Hmm.