Adds missing pink ik controller documentation page

[michaellin6]

Description

This PR fixes some missing documentation related to changes in #3149

Fixes # (issue)

Missing documentation page for pink IK controller

Type of change

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

Checklist

• I have run the pre-commit checks 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

[Mayankm96]

Is it possible to keep this inside here instead of having its own page?

https://github.com/isaac-sim/IsaacLab/blob/main/docs/source/api/lab/isaaclab.controllers.rst

Also, I think you need to add the non-RTD dependencies in this list since those dependencies are not available on the CI-build unless we explicitly install them: https://github.com/isaac-sim/IsaacLab/blob/main/docs/conf.py#L130-L131