Format some comments

Marlin/Configuration_adv.h

@@ -481,18 +481,22 @@
 // before a min_temp_error is triggered. (Shouldn't be more than 10.)
 //#define MAX_CONSECUTIVE_LOW_TEMPERATURE_ERROR_ALLOWED 0
 
-// The number of milliseconds a hotend will preheat before starting to check
-// the temperature. This value should NOT be set to the time it takes the
-// hot end to reach the target temperature, but the time it takes to reach
-// the minimum temperature your thermistor can read. The lower the better/safer.
-// This shouldn't need to be more than 30 seconds (30000)
+/**
+ * The number of milliseconds a hotend will preheat before starting to check
+ * the temperature. This value should NOT be set to the time it takes the
+ * hot end to reach the target temperature, but the time it takes to reach
+ * the minimum temperature your thermistor can read. The lower the better/safer.
+ * This shouldn't need to be more than 30 seconds (30000)
+ */
 //#define MILLISECONDS_PREHEAT_TIME 0
 
 // @section extruder
 
-// Extruder runout prevention.
-// If the machine is idle and the temperature over MINTEMP
-// then extrude some filament every couple of SECONDS.
+/**
+ * Extruder runout prevention.
+ * If the machine is idle and the temperature over MINTEMP
+ * then extrude some filament every couple of SECONDS.
+ */
 //#define EXTRUDER_RUNOUT_PREVENT
 #if ENABLED(EXTRUDER_RUNOUT_PREVENT)
   #define EXTRUDER_RUNOUT_MINTEMP 190