Drop the redundant documentation/marketing/ nesting inherited from the
plugin repos, so files sit at marketing/<plugin>/<page>.md. These paths
become raw URLs pasted into Elementor pages and ACF fields, so they are
much cheaper to change now than once sites reference them.
Fixes the four cross-plugin links for their new depth, and corrects the
README, which still pointed at the abandoned per-repo documentation/
folders instead of this repo.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>