Adds note that Pink actions and envs are Linux only (#7542)

# Description

Pink IK is a Linux only package. Add note in docs to indicate this.

Fixes # (issue)

Windows users may not have been aware that Pink actions and envs are
Linux only.

## Type of change

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applicable. -->

- Bug fix (non-breaking change which fixes an issue)
- Documentation update

## Release backport

- [x] <!-- backport-active-release --> Backport this pull request to the
active release branch after it merges into `develop`


## Checklist

Docker and GPU tests run on demand. Push the commits you want tested,
then
comment `run-ci` on the pull request.

- [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 added a changelog fragment under
`source/<pkg>/changelog.d/` for every touched package (do **not** edit
`CHANGELOG.rst` or bump `extension.toml` — CI handles that)
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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Author: peterd-NV

docs/source/api/lab/isaaclab.envs.mdp.rst

@@ -12,6 +12,11 @@ Observations
 Actions
 -------
 
+.. important::
+
+    ``PinkInverseKinematicsAction`` is supported only on Linux. Tasks configured with this action cannot run on
+    Windows because Pink IK and its dependencies are not available there.
+
 .. automodule:: isaaclab.envs.mdp.actions
 
 .. automodule:: isaaclab.envs.mdp.actions.actions_cfg

docs/source/overview/imitation-learning/humanoids_imitation.rst

@@ -11,6 +11,9 @@ This page covers data generation and imitation learning workflows for humanoid r
 
 .. important::
 
+   The Isaac Lab Mimic workflows and Pink IK tasks on this page are supported only on Linux.
+   Pink IK and its dependencies are not available on Windows.
+
    Complete the tutorial in :ref:`Synthetic Data Generation and Imitation Learning with Isaac Lab Mimic <teleoperation-imitation-learning>`
    before proceeding with the following demonstrations to
    understand the data collection, annotation, and generation steps of Isaac Lab Mimic.