doc to ai conversion can actually mean several things, with the most obvious being using text from some document when making Adobe Illustrator graphics.
This is not conversion per se on file to file export basis, but you can usually import or reuse texts and import them as objects for example that you can alter and work with. Most vector graphics tools that are used to make publications offer this function under one name or another.
You can certainly find many guides and tutorials about this subject on the Internet.
Updated: November 3, 2023