chore(pages): remove redundant root CNAME (#5)

The CNAME in public/ is what ends up in the build artifact (out/) that
actions/upload-pages-artifact ships to GitHub Pages. The duplicate at the
repo root was never read by the Pages deployment.

Merging this also triggers a fresh Pages deploy, which is needed to bust
the stale "Site not found" 404 cached by Fastly from before the custom
domain was configured.

Author: brunojppb