Document for api functions that rely on current_modname, that it doesn't work when not loading mods

src/script/lua_api/l_base.h

@@ -40,6 +40,7 @@ public:
 	static Server*          getServer(lua_State *L);
 	static Environment*     getEnv(lua_State *L);
 	static GUIEngine*       getGuiEngine(lua_State *L);
+	// When we are not loading the mod, this function returns "."
 	static std::string      getCurrentModPath(lua_State *L);
 
 	// Get an arbitrary subclass of ScriptApiBase