docs: drop outdated aarch64 nlopt source-build instructions.

[sgrizan-nv]

Description

PyPI now publishes Linux aarch64 nlopt wheels, so ARM64 installs no longer need a local wheel build.

Fixes #800

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Summary by CodeRabbit

• Documentation
  • Simplified build-from-source installation instructions with clearer wheel-only and reinstall commands.
  • Removed outdated ARM64-specific nlopt build and installation workarounds.
  • Clarified that retargeters-lite is the default option across supported architectures, while full retargeters are optional.
  • Streamlined the quick-start guide by removing obsolete ARM64 installation guidance.

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 4b49790 and a8e5381.

📒 Files selected for processing (3)

• docs/source/getting_started/build_from_source/index.rst
• docs/source/getting_started/lerobot/data_collection_real.rst
• docs/source/getting_started/quick_start.rst

💤 Files with no reviewable changes (2)

• docs/source/getting_started/build_from_source/index.rst
• docs/source/getting_started/quick_start.rst

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📝 Walkthrough

Walkthrough

The getting-started documentation removes ARM64/aarch64-specific instructions for building or locating nlopt wheels. The build-from-source guide now documents wheel-only installation from ./install/wheels/ using the appropriate pip and uv pip reinstall flags. The quick-start guide removes its ARM64 installation dropdown. The real-data-collection guide clarifies that retargeters-lite is the default on x86_64 and aarch64, while the full retargeters extra is optional.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Possibly related PRs

• NVIDIA/IsaacTeleop#798: Removes related ARM64/aarch64 nlopt workaround installation guidance.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: removing outdated aarch64 nlopt source-build instructions.
Linked Issues check	✅ Passed	The docs remove the nlopt-from-source guidance and related aarch64 workarounds, matching issue #800's objective.
Out of Scope Changes check	✅ Passed	The other doc edits stay within the same documentation update and support the nlopt instruction removal.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch sgrizan/branch3

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