[DOC] Add detailed descriptions of memory space options

[HugoPhibbs]

Which documentation should be updated? Should add docs of what memory space options one can use. I wasn't able to find anything in the docs after scouring it a bit. I think would be nice to have to save users from having to manually look into the source code - which may lead to misinterpretations.

Virtually adding docs for the enum vals below:

// allocator.h
/**
 * @brief Space where memory is stored (also called Kind in some contexts)
 * 
 */
enum matxMemorySpace_t {
  MATX_MANAGED_MEMORY,
  MATX_HOST_MEMORY,
  MATX_HOST_MALLOC_MEMORY,
  MATX_DEVICE_MEMORY,
  MATX_ASYNC_DEVICE_MEMORY,
  MATX_INVALID_MEMORY
};

Please provide any links to existing documentation where the updates are needed Perhaps a hyper link from the make_tensor page right to the space options - given that the space option is a function param.