Change the way out parameters are defined.

The creation, allocation and capability-query functions use out parameters to return the created/allocated object (and the actual return value for errors). However not all languages support this and automatically mapping the pointer arguments to return values can be tricky.

Instead marking them explicitly will make it clearer where the result goes.

``` xml

VkResult vkCreateInstance
const VkInstanceCreateInfo* pCreateInfo
const VkAllocationCallbacks* pAllocator
VkInstance* pInstance


VkResult vkEnumeratePhysicalDevices
VkInstance instance
uint32_t* pPhysicalDeviceCount
VkPhysicalDevice* pPhysicalDevices

```

Review the XML command definitions for creation, allocation, and capability-query functions, starting with the vkCreateInstance and vkEnumeratePhysicalDevices examples in the issue. Trace how their parameters are consumed and mapped, then verify that the affected definitions explicitly identify returned objects and error results across the relevant commands.

Written by the indexing model from the issue text.