The documentation does not has example of showing stdout of a step as output parameter.

This is not correct, there is an example on an adjacent page: https://argo-workflows.readthedocs.io/en/latest/walk-through/scripts-and-results/.

As such this seems redundant, and in its current state, explains less than the existing example. It also re-introduces result without a description.

1. The existing example from the link refers when a step is using the script, using source tag. And the stdout of the script is stored in result output parameter.
2. The example provided as part of this pull request
   a). does not use source tag.
   b) its an example of
   below statement
   "Containers¶
   Container steps and tasks also have their standard output captured in the result parameter."

at https://argo-workflows.readthedocs.io/en/latest/walk-through/output-parameters/

c) results is already mentioned in same url above

That rationale makes more sense -- you didn't mention the container portion in your descriptions or titles initially. I've modified the title to make that clear.

Otherwise, see my comment in the issue, we may want to move the entire "result" section out of this page and into the other page (including your example).