make documentation equal for all three classes.

opm/core/simulator/SimulatorTimer.hpp

@@ -95,10 +95,10 @@ namespace Opm
         /// Note: if done(), it is an error to call report().
         void report(std::ostream& os) const;
 
-        /// Next step.
+        /// advance time by currentStepLength
         SimulatorTimer& operator++();
 
-        /// Next step.
+        /// advance time by currentStepLength
         void advance() { this->operator++(); }
 
         /// Return true if op++() has been called numSteps() times.

opm/core/simulator/SimulatorTimerInterface.hpp

@@ -75,7 +75,7 @@ namespace Opm
         /// beginning of the current time step [s].
         virtual double simulationTimeElapsed() const = 0;
 
-        /// advance timer to the next time step
+        /// advance time by currentStepLength
         virtual void advance() = 0 ;
 
         /// Return true if timer indicates that simulation of timer interval is finished