update readme

README.md

@@ -50,6 +50,7 @@ Main application sources located at `src/app` folder, by following principles:
 
 * Every file extends one of GTK 4 Widgets according to subject (e.g. `class Browser : public Gtk::ApplicationWindow`)
 * `src/app` does not contain other class entities like models or libraries (another folders and namespaces at `src` root are reserved for these needs)
+* Namespaces match filesystem path, where directories are named lowercase
 * Every file work with it own, 1th level child only, to prevent massive logic levels keeping in mind
 * To access any children features, deeper or higher than 1th level of current class, use delegation methods (actions, getters and setters)
 * One file - one class. If the file requires additional (GTK) component, this component should be placed at similar folder with same name as parent filename. So we have simple hierarchy navigation logic - from app to window, from window to it container, etc.