Link to universal_[host_pinned_][allocator|vector] in the docs

Also expose `thrust::universal_host_pinned_allocator`

Fixes: NVIDIA#4106

Author: bernhardmgruber

docs/thrust/api_docs/containers.rst

@@ -9,3 +9,5 @@ Containers
 
    ${repo_docs_api_path}/*host__vector*
    ${repo_docs_api_path}/*device__vector*
+   ${repo_docs_api_path}/*universal_vector*
+   ${repo_docs_api_path}/*universal_host_pinned_vector*

docs/thrust/api_docs/memory_management/allocators.rst

@@ -6,9 +6,10 @@ Allocators
   - :cpp:class:`thrust::device_allocator <thrust::device_allocator>`
   - :cpp:class:`thrust::device_malloc_allocator <thrust::device_malloc_allocator>`
   - :cpp:class:`thrust::device_new_allocator <thrust::device_new_allocator>`
+  - :cpp:class:`thrust::universal_allocator <thrust::universal_allocator>`
+  - :cpp:class:`thrust::universal_host_pinned_allocator <thrust::universal_host_pinned_allocator>`
   - :cpp:class:`thrust::mr::allocator <thrust::mr::allocator>`
   - :cpp:class:`thrust::mr::stateless_resource_allocator <thrust::mr::stateless_resource_allocator>`
-  - :cpp:class:`thrust::mr::stateless_resource_allocator <thrust::mr::stateless_resource_allocator>`
 
 .. toctree::
    :glob:

thrust/thrust/universal_allocator.h

@@ -50,6 +50,13 @@ THRUST_NAMESPACE_BEGIN
  */
 using thrust::system::__THRUST_DEVICE_SYSTEM_NAMESPACE::universal_allocator;
 
+/*! \brief An allocator which creates new elements in memory accessible by both hosts and devices. Uses pinned memory
+ *         when the system supports it.
+ *
+ *  \see https://en.cppreference.com/w/cpp/named_req/Allocator
+ */
+using thrust::system::__THRUST_DEVICE_SYSTEM_NAMESPACE::universal_host_pinned_allocator;
+
 /*! \p universal_ptr stores a pointer to an object allocated in memory accessible
  *  to both hosts and devices.
  *