Use more elegant singleton and fix spell bug.

example/src/AppInfo.h

@@ -13,7 +13,7 @@ class AppInfo : public QObject
 private:
     explicit AppInfo(QObject *parent = nullptr);
 public:
-    SINGLETONG(AppInfo)
+    SINGLETON(AppInfo)
 };
 
 #endif // APPINFO_H

example/src/helper/SettingsHelper.h

@@ -16,7 +16,7 @@ class SettingsHelper : public QObject
 private:
     explicit SettingsHelper(QObject* parent = nullptr);
 public:
-    SINGLETONG(SettingsHelper)
+    SINGLETON(SettingsHelper)
     ~SettingsHelper() override;
     void init(char *argv[]);
     Q_INVOKABLE void saveDarkMode(int darkModel){save("darkMode",darkModel);}

example/src/singleton.h

@@ -34,7 +34,7 @@ T* Singleton<T>::getInstance() {
     return instance;
 }
 
-#define SINGLETONG(Class)                              \
+#define SINGLETON(Class)                              \
 private:                                               \
     friend class Singleton<Class>;              \
     friend struct QScopedPointerDeleter<Class>;        \