fix typo

Marlin/Configuration_adv.h

@@ -278,7 +278,7 @@
 //===========================================================================
 //=============================Additional Features===========================
 //===========================================================================
-.
+
 #define SD_FINISHED_STEPPERRELEASE true  //if sd support and the file is finished: disable steppers?
 #define SD_FINISHED_RELEASECOMMAND "M84 X Y Z E" // You might want to keep the z enabled so your bed stays in place.