add flight recorder tutorial (#3814)

Summary:
Add a tutorial for debugging single-rank hangs in distributed PyTorch
jobs using the TorchComms Flight Recorder, covering both aggregated text
dump analysis and per-rank pickle-based CLI detection workflows.

Co-authored-by: Tushar Jain <tushar00jain@users.noreply.github.com>
Co-authored-by: sekyondaMeta <127536312+sekyondaMeta@users.noreply.github.com>

Author: tushar00jain

distributed.rst

@@ -211,6 +211,7 @@ Custom Extensions
    intermediate/rpc_param_server_tutorial
    intermediate/rpc_async_execution
    intermediate/monarch_distributed_tutorial
+   intermediate/debug_hangs_with_flight_recorder
    advanced/rpc_ddp_tutorial
    advanced/generic_join
    beginner/distributed_training_with_ray_tutorial

index.rst

@@ -724,6 +724,13 @@ Welcome to PyTorch Tutorials
    :link: intermediate/monarch_distributed_tutorial.html
    :tags: Parallel-and-Distributed-Training
 
+.. customcarditem::
+   :header: Debugging Hangs with Flight Recorder Using TorchComms and Debug Server
+   :card_description: Diagnose hangs using the TorchComms Flight Recorder and Debug Server periodic dumps.
+   :image: _static/img/thumbnails/cropped/generic-pytorch-logo.png
+   :link: intermediate/debug_hangs_with_flight_recorder.html
+   :tags: Parallel-and-Distributed-Training,Debugging
+
 .. Edge
 
 .. customcarditem::