loader: Fix function name in interface doc
loader: Fix function name in interface doc

There is no "vk_icdGetLoaderICDInterfaceVersion" function. The correct name is "vk_icdNegotiateLoaderICDInterfaceVersion."
KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools