Integrate Accelerator API to intermediate_source/dist_tuto.rst (#3529)

## Motivation
- Enhance distributed tutorial: integrate Accelerator API for backend
selection and add XCCL backend details
- 
## Description
- Integrate the Accelerator API into the
`intermediate_source/dist_tuto.rst` to support multiple accelerators and
improve backend initialization.
- 

---------

Signed-off-by: jafraustro <jaime.fraustro.valdez@intel.com>
Co-authored-by: sekyondaMeta <127536312+sekyondaMeta@users.noreply.github.com>
Co-authored-by: Svetlana Karslioglu <svekars@meta.com>

Author: 3 people

intermediate_source/dist_tuto.rst

@@ -470,9 +470,10 @@ Communication Backends
 
 One of the most elegant aspects of ``torch.distributed`` is its ability
 to abstract and build on top of different backends. As mentioned before,
-there are multiple backends implemented in PyTorch.
-Some of the most popular ones are Gloo, NCCL, and MPI.
-They each have different specifications and tradeoffs, depending
+there are multiple backends implemented in PyTorch. These backends can be easily selected
+using the `Accelerator API <https://pytorch.org/docs/stable/torch.html#accelerators>`__,
+which provides a interface for working with different accelerator types.
+Some of the most popular backends are Gloo, NCCL, and MPI. They each have different specifications and tradeoffs, depending
 on the desired use case. A comparative table of supported functions can
 be found
 `here <https://pytorch.org/docs/stable/distributed.html#module-torch.distributed>`__.
@@ -492,12 +493,13 @@ distributed SGD example does not work if you put ``model`` on the GPU.
 In order to use multiple GPUs, let us also make the following
 modifications:
 
-1.  Use ``device = torch.device("cuda:{}".format(rank))``
-2. ``model = Net()`` :math:`\rightarrow` ``model = Net().to(device)``
-3.  Use ``data, target = data.to(device), target.to(device)``
+1. Use Accelerator API ``device_type = torch.accelerator.current_accelerator()``
+2. Use ``torch.device(f"{device_type}:{rank}")``
+3. ``model = Net()`` :math:`\rightarrow` ``model = Net().to(device)``
+4.  Use ``data, target = data.to(device), target.to(device)``
 
-With the above modifications, our model is now training on two GPUs and
-you can monitor their utilization with ``watch nvidia-smi``.
+With these modifications, your model will now train across two GPUs.
+You can monitor GPU utilization using ``watch nvidia-smi`` if you are running on NVIDIA hardware.
 
 **MPI Backend**
 
@@ -553,6 +555,7 @@ more <https://www.open-mpi.org/faq/?category=running#mpirun-hostfile>`__)
 Doing so, you should obtain the same familiar output as with the other
 communication backends.
 
+
 **NCCL Backend**
 
 The `NCCL backend <https://github.com/nvidia/nccl>`__ provides an
@@ -561,6 +564,14 @@ tensors. If you only use CUDA tensors for your collective operations,
 consider using this backend for the best in class performance. The
 NCCL backend is included in the pre-built binaries with CUDA support.
 
+**XCCL Backend**
+
+The `XCCL backend` offers an optimized implementation of collective operations for XPU tensors.
+If your workload uses only XPU tensors for collective operations,
+this backend provides best-in-class performance.
+The XCCL backend is included in the pre-built binaries with XPU support.
+
+
 Initialization Methods
 ~~~~~~~~~~~~~~~~~~~~~~