Hack: automatically generate KatibClient.md doc from `post_gen.py`

[anencore94]

/kind feature

Describe the solution you'd like [A clear and concise description of what you want to happen.]

There is a script for generating api docs from swagger, but doesn't generate KatibClient.md for now. So we should modify manually when api changed.

There was a discussion for this

• https://github.com/kubeflow/katib/pull/1630#discussion_r693344353

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[andreyvelich]

/lifecycle frozen

[andreyvelich]

Should be fixed by this: https://github.com/kubeflow/katib/issues/2081