message: Add known issues to distributed training docs
  Summary: !docs-only
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, #tech_docs, alfiee
  Subscribers: jayniep
  Maniphest Tasks: T70244
diff: @@ -34,3 +34,9 @@ PopDistStrategy examples
  ########################
  There are examples for `PopDistStrategy` in the Graphcore :tutorials-repo:`feature examples on GitHub <feature_examples/tensorflow2/popdist>`.
  +
  +Limitations and known issues
  +############################
  +
  +* Replicated Tensor Sharding (RTS) is not supported for distributed training
  + with ``PopDistStrategy``.
  