TEP-0114: Custom Tasks Beta - Documentation

[jerop]

In TEP-0114: Custom Tasks Beta, we proposed migrating Custom Tasks and Runs to beta.

Ahead of the promotion, we agreed to expand the documentation for Custom Tasks and Runs. This issue tracks the documentation work.

[vsinghai]

/assign

[XinruZhang]

/assign

[XinruZhang]

Thanks for the well-structrued todos @jerop! As we discussed offline, I'm extending the TODOs listed in #5158 (comment). I don't have the edit permission on the comment so I'm just copying over and add a bit of details.

• Migration guide for v1alpha1.Run --> v1beta1.CustomRun
  • Prepare a migration doc, refer to the migration doc in the runs.md and pipelines.md
  • Remove illustration about how to use alpha run
  • Add illustration about how to use beta customrun
    • Update runs.md e.g. adding missing fields in "configuration" section
    • Update pipelines.md#using-custom-tasks e.g. providing practical examples with references to end-to-end examples that use wait custom task
    • Once the test controller for v1beta1.CustomRun is ready, add it as an example in pipelines.md#using-custom-tasks
• UX improvement
  • Add a table of known Custom Tasks to runs.md for visibility - can get started with the list of eight in TEP-0114

[jerop]

Completed in #5677 and #5850