Python visualization dev guide link is broken

[paveldournov]

What happened:
Page: https://github.com/kubeflow/pipelines/blob/master/developer_guide.md#python-based-visualizations

link is broken and leads to a 404 error. The link is pointing to:
https://github.com/kubeflow/pipelines/blob/master/backend/src/apiserver/visualization/developer_guide.md

What did you expect to happen:
Link to the developer guide of the visualization components.

[rmgogogo]

correct link here:
https://github.com/kubeflow/pipelines/blob/master/backend/src/apiserver/visualization/README.md

[SuperKogito]

I think broken links are a common issue and a radical solution to this problem is automatically checking and reporting them. Luckily the new GitHub actions and workflows help with that. I recently wrote an action that just does that. URLs-checker will check and report broken links, which is useful to spot similar issues to this one.

[rmgogogo]

Thanks SuperKogito!
I don't have permission to setup Action for this project. Let's wait after admin be back from vacation.