Looks like I transposed the acronym. It's DMCA, or Digital Millennium Copyright Act: https://www.copyright.gov/dmca/.

Adding a copyright indication at the bottom of your work doesn't really do anything. If you're publishing on Medium, the work alreayd contains copyrights held by you. Stating it again is just restating the obvious. It also does nothing to prevent people from "adapting" your words. Those who don't care about copyrights won't care you've added a notice.