docs: add development journey section

Agent-Logs-Url: https://github.com/ThisIs-Developer/Markdown-Viewer/sessions/b08a4e87-065d-4dba-86ae-061a26ec9c52

Co-authored-by: ThisIs-Developer <109382325+ThisIs-Developer@users.noreply.github.com>

Author: Copilot

README.md

@@ -35,6 +35,7 @@
 - [Showcase](#showcase)
 - [Contributing](#contributing)
 - [Contributors](#contributors)
+- [Development Journey](#development-journey)
 - [License](#license)
 - [Contact](#contact)
 
@@ -204,6 +205,12 @@ Thanks to everyone who has contributed to Markdown Viewer.
 
 ---
 
+## 📈 Development Journey
+
+Markdown Viewer has grown from a lightweight Markdown parser into a full-featured, professional application with advanced rendering, workflow, and export capabilities. Compare the [current version](https://markdownviewer.pages.dev/) with the [original version](https://a1b91221.markdownviewer.pages.dev/) to see the progress in UI design, performance optimization, and feature depth.
+
+---
+
 ## License
 
 This project is licensed under the Apache License. See [LICENSE](LICENSE) for details.