Add config idea comment

src/main.cpp

@@ -83,7 +83,8 @@ int main(int argc,  char* argv[]) {
 
         // TODO Introduce config file with settting for this path and install it
         // when doing  "make install". Only  use the hard-coded default  when no
-        // config can be found.
+        // config can be found. This means we need a system-wide config in /etc,
+        // which can be overridden by a config file in the user's $HOME.
         std::string plugin_dir {"/usr/local/share/screensaver/plugins"};
         sc::plugin<ScreensaverPlugin>::scan_plugins(plugin_dir, "saver");