[Doc] Migrate shifted=True callers to legacy/compact + docstring polish

[vmoens]

Stack from ghstack (oldest at bottom):

• -> [Doc] Migrate shifted=True callers to legacy/compact + docstring polish #3776
• [Example] Expose compact GAE cat dimension #3775
• [Example] Add Isaac RNN PPO rollout mode flags #3769
• [Example] Isaac Lab RNN PPO with compact memory + knowledge-base notes #3763
• [BugFix] Fix GAE compact path bias on recurrent value nets at internal truncations #3771

---

• Switch benchmarks/test_objectives_benchmarks.py, examples/rlhf/utils.py
  and knowledge_base/ISAACLAB.md callers from the deprecated
  shifted=True to the explicit shifted="legacy" /
  shifted="compact" API.
• Update data_layout.rst to mention the new shifted modes instead of
  single_call=True.
• Expand the compact_obs docstring on Collector to call out clean
  composition with GAE(shifted="compact").
• Clarify in the GAE docstring how shifted="legacy", shifted="compact"
  and shifted=False differ in the recurrent-value-net case.
• Clarify on MultiCollector that policy_version / get_policy_version
  expose only the parent-side tracker state; the per-frame
  "policy_version" tensor is the source of truth for collected data.
• Minor formatting fix in examples/collectors/isaaclab_rnn_ppo_memory.py.

Authored with Claude.

Co-authored-by: Cursor cursoragent@cursor.com

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/rl/3776

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• Run pull request jobs on OSDC runners in shadow mode

❌ 1 New Failure, 2 Unrelated Failures

As of commit 94e63df with merge base 5d11fa3 ():

NEW FAILURE - The following job has failed:

• Libs Tests on Linux / unittests-sklearn (3.10, 12.8) / linux-job (gh)
  test/libs/test_datasets.py::TestOpenML::test_env[batch_size0-shuttle]

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Build Windows Wheels / pytorch/rl / build-wheel-py3_10-cpu (gh) (trunk failure)
  Process completed with exit code 1.
• Build Windows Wheels / pytorch/rl / upload / upload-wheel-py3_10-cpu (gh) (trunk failure)
  Unable to download artifact(s): Artifact not found for name: pytorch_rl__3.10_cpu_x64

This comment was automatically generated by Dr. CI and updates every 15 minutes.