getting-started.md

1. define the state S, input I and output O of the state

   class S
   {
       // ...
   };
   class I
   {
       // ...
   };
   class O
   {
       // ...
   };

2. inherit the state machine class based on sm::SM<S, I, O> and override the transition function tf and output function of and function goon

   class StateMachine : public sm::SM<S, I, O>
   {
       virtual S tf(const I &i, const S &s) override
       {
           // ...
       }
       virtual O of(const I &i, const S &s) override
       {
           // ...
       }
       virtual bool goon(const S &s) override
       {
           // ...
       }
   };

3. create state machine instances in main function and run

   int main()
   {
       auto sm = StateMachine([] { return I::MSG; }, [](const O &) { std::cout << "ok" << std::endl; });
       sm.run(S::INIT);
       return 0;
   }