Flatten marketing paths ahead of wiring up the websites

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>

marketing/dotjuice-elementor-tools/widgets/markdown-widget.md

@@ -0,0 +1,29 @@
+# Markdown Widget
+
+Embed a live Markdown file directly into your page — always showing the current version, with no copy-pasting.
+
+## The problem it solves
+
+Documentation, changelogs, and README files usually live in Markdown format in a repository, separate from your WordPress site. Keeping a WordPress page in sync with them means manually copying the content across every time it changes.
+
+## How it helps
+
+Point the Markdown Widget at any Markdown file URL — a GitHub README, a changelog, a docs page — and it fetches the file on your server and renders it as proper HTML headings, lists, code blocks, and links. Because the fetch happens server-side, it works with private and self-hosted repositories too, not just sources that permit cross-origin requests.
+
+## The result
+
+A documentation or changelog page on your WordPress site that's always current, sourced directly from wherever the Markdown file actually lives.
+
+## One document per product, without one page per product
+
+The widget also comes with a `[dj_markdown]` shortcode, which works anywhere a widget can't go — inside a WooCommerce product tab, a text editor, or a template.
+
+Instead of a fixed URL, the shortcode can read the URL from a custom field on whatever is being displayed:
+
+```
+[dj_markdown acf_field="changelog_url"]
+```
+
+Add a URL field to your products, place that single shortcode once, and every product shows its own document. A software shop can give each plugin a live Changelog tab that updates itself from the repository — no per-product page building, and nothing to maintain by hand as versions ship.
+
+It reads ACF fields where ACF is installed and falls back to standard custom fields where it isn't, so it fits whichever setup a site already uses.