Add documentation and doctest for KMEANS and AD commands

[jackiehanyang]

Is your feature request related to a problem? Please describe.
This PR introduced two new commands KEMANS and AD. Need to add documentation and doctest correspondingly.

Describe the solution you'd like
To have documentation and doctest that cover KMEANS and AD command usage.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.