Add a way to validate command examples

[swissspidy]

Looking at wp-cli/cache-command#120, I am wondering if there's a good way to catch such issues across all our repos, to ensure the documentation is correct.

Maybe extract all the examples, run them and compare the results. Could be a one off thing with AI, or something automated.

[trepmal]

It may be worth noting that in that PR the example command+result was not invalid, just confusing.

[swissspidy]

Indeed. That is an argument in favor of a one-off AI-powered review.