docs: add OOpenWebUI official newsletter featured recognition to Smart Mind Map, Markdown Normalizer, and Prompt Plus (#52)

* Initial plan

* docs: add OpenWebUI official newsletter featured recognition

- Add newsletter featured callout to Smart Mind Map README.md, README_CN.md, and docs
- Add newsletter featured callout to Markdown Normalizer README.md, README_CN.md, and docs
- Add newsletter featured badge to Prompt Plus in root README.md and README_CN.md
- Reference both newsletters: Jan 28, 2026 and Feb 3, 2026

Co-authored-by: Fu-Jie <33599649+Fu-Jie@users.noreply.github.com>

* docs: fix newsletter links to match actual featured issue per plugin

- Smart Mind Map: link only to Feb 3, 2026 (second newsletter)
- Markdown Normalizer: link only to Jan 28, 2026 (first newsletter)
- Prompt Plus (root READMEs): already correct, no change needed

Co-authored-by: Fu-Jie <33599649+Fu-Jie@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Fu-Jie <33599649+Fu-Jie@users.noreply.github.com>

docs/plugins/actions/smart-mind-map.md

@@ -5,6 +5,8 @@
 
 Intelligently analyzes text content and generates interactive mind maps for better visualization and understanding.
 
+> 🏆 **Featured by OpenWebUI Official** — Recommended in the official OpenWebUI Community Newsletter: [February 3, 2026](https://openwebui.com/blog/open-webui-community-newsletter-february-3rd-2026)
+
 ---
 
 ## Overview