isaac-sim#3489)

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Updates the Isaac Lab Mimic doc tutorials according to prior reviewer
feedback.
Changes:

1. Clarify demo success criteria for Demo 2 (humanoid pouring task)
2. Add visualization at the start of Demo 2 to clearly indicate that it
is a different task from Demo 1.
3. Document the dataset of Demo 2

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applicable. -->

- Documentation update

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- [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
- [ ] 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
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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(cherry picked from commit 137106d)

isaac-sim#3489)

<!--
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.
-->

Updates the Isaac Lab Mimic doc tutorials according to prior reviewer
feedback.
Changes:

1. Clarify demo success criteria for Demo 2 (humanoid pouring task)
2. Add visualization at the start of Demo 2 to clearly indicate that it
is a different task from Demo 1.
3. Document the dataset of Demo 2

<!-- As you go through the list, delete the ones that are not
applicable. -->

- Documentation update

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

<!--
Example:

| Before | After |
| ------ | ----- |
| _gif/png before_ | _gif/png after_ |

To upload images to a PR -- simply drag and drop an image while in edit
mode and it should upload the image directly. You can then paste that
source into the above before/after sections.
-->

- [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
- [ ] 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
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

<!--
As you go through the checklist above, you can mark something as done by
putting an x character in it

For example,
- [x] I have done this task
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(cherry picked from commit 137106d)