[codingdave]

This sounds like basic content management. Give them an admin UI - Put an editor on-screen, load/save the various data, pull the saved value into your code as appropriate. Include some input validation on your editor, and it is a basic CRUD form. Maybe a little more complex if you include a workflow so that their changes get tested before going live.

[apothegm]

This. A database field and a textarea, with old versions preserved in the DB.