We can't modify the tour that way without developer intervention.
Only three parts of the tour are editable by diamond moderators:
The blurb at the top—we can change its text. That's the paragraph starting with “RPG Stack Exchange is a question and answer site for...”
The example question shown in the first section can be swapped for any other.
The on/off ...
There is a help article dedicated to this, and we have our own guidance we can link.
How do I write a good answer?. Link this article if you feel the need to leave more detailed guidance about writing good answers that is not covered in the tour.
We also have our citation expectation meta that is even better and more specific than the help article. I prefer ...
The tour is only a basic introduction to the site
The tour gives a basic, high level introduction to the site. And it's hard to give an actually useful definition of what a good answer is, especially that fits into a place like the tour. That fits better into the help center, and for any aspects which aren't covered by the (non-editable) articles there, meta....