add sample alert text, which we do offer on the redesign tips page
fix the screenshot reference and improve the alt text
PR Checklist
[x] Test Cloud.gov Pages preview link for your branch for functionality - make sure all links and buttons work, javascript works as intended, and updates display as expected
[x] Conduct a HemingwayApp review of the content for plain language. Request plain language review in #helpwanted if needed before merging this PR - used previous review approval, since copying text from another page.
[x] Conduct a Lighthouse Audit via Chrome Developer Tools. Identify any issues that must be addressed before merging, and fix
[x] Ensure no non-public information is published in the commit messages
PR Checklist