Update README.md

Author: theangryangel

README.md

@@ -2,7 +2,9 @@
 
 # Addons for Odoo
 
-This repository houses addons for many areas of Odoo. It is an amalgamation of multiple previous repositories (GlodoUK/sale, web, etc.)
+This repository houses addons for many areas of Odoo. It is an amalgamation of multiple previous repositories (GlodoUK/sale, web, etc.).
+
+Please see our sibling repository for proprietary modules: [GlodoUK/odoo-addons-proprietary](https://github.com/GlodoUK/odoo-addons-proprietary).
 
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