…sim#3621) (isaac-sim#3627)

# Description

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Isaac Lab Mimic section is disjoint from [IsaacLabEvalTask
repo](https://github.com/isaac-sim/IsaacLabEvalTasks/tree/main) which
uses Mimic to generate Nut pouring task and Pipe sorting task for GR00T
post-training and closedloop evaluation. Added a pointer in the doc.

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## Type of change

Documentation update

## Checklist

- [x] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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(cherry picked from commit b7004f4)

# Description

<!--
Thank you for your interest in sending a pull request. Please make sure
to check the contribution guidelines.

Link:
https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html

💡 Please try to keep PRs small and focused. Large PRs are harder to
review and merge.
-->

Please include a summary of the change and which issue is fixed. Please
also include relevant motivation and context.
List any dependencies that are required for this change.

Fixes # (issue)

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discussions on the proposed pull request.
This makes it easier for the community to keep track of what is being
developed or added, and if a given feature
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## Type of change

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applicable. -->

- Bug fix (non-breaking change which fixes an issue)
- New feature (non-breaking change which adds functionality)
- Breaking change (existing functionality will not work without user
modification)
- Documentation update

## Screenshots

Please attach before and after screenshots of the change if applicable.

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## Checklist

- [ ] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [ ] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [ ] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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