*Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.*
fix some typos
*List which issues are fixed by this PR. You must list at least one issue.*
*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*
This example was incorrectly throwing away results from a query when multiple queries were pending at once. Thanks to @sun-jiao in https://github.com/flutter/flutter/pull/127019#issuecomment-1552347037 for pointing this out.
I also added a quick `Text` widget explaining what to do to use the examples. Since there are only three small possible `options`, it's easy to type into the field and not get any results and wonder what's wrong.
