Add promo domains for sale section

Added promotional domains for sale to the README.

Author: app-generator

README.md

@@ -9,6 +9,16 @@ The product is designed to deliver the best possible user experience with highly
 
 <br />
 
+## `PROMO` Domains for sale
+
+- 👉 **[AppSeed.us - $49k](https://appseed.us/)**
+- 👉 **[Admin-Dashboards.com - $15k](https://www.admin-dashboards.com/)**
+- 👉 **[UI-Themes.com - $5k](https://ui-themes.com/)**
+- 👉 **[Simpllo.com - $10k](https://www.simpllo.com/)**
+- 👉 **[123SiteBuilder.net - $5k](https://www.123sitebuilder.net/)**
+
+<br />
+
 ## Features
 
 - Simple, Easy-to-Extend codebase