adding comments

src/minefield.cpp

@@ -25,6 +25,7 @@ void MineField::timerTick() {
     timerSignal.emit(m_time);
     start = std::chrono::system_clock::now();
   }
+  //I should use std::duration to represent the time instead
 }
 
 void MineField::initBombs(int x, int y) {
@@ -46,7 +47,7 @@ void MineField::initBombs(int x, int y) {
   //init the timer to zero and start the timer thread
   m_time = 0;
   timerThread = std::thread(&MineField::timerTick, this);
-  timerThread.detach(); //not sure if this is okay
+  timerThread.detach(); //not sure if this is okay (better to call join() when I set the condition to stop the thread)
 }
 
 bool MineField::openCell(int x, int y) {