fix grayscale test pins

Author: ladyada

examples/ThinkInk_gray4/ThinkInk_gray4.ino

@@ -9,9 +9,11 @@
 
 #include "Adafruit_ThinkInk.h"
 
-/* breakout */
-
-#define SRAM_CS    -1
+#define EPD_CS     10
+#define EPD_DC      9
+#define SRAM_CS     11
+#define EPD_RESET   5 // can set to -1 and share with microcontroller Reset!
+#define EPD_BUSY    7 // can set to -1 to not use a pin (will wait a fixed delay)
 
 //ThinkInk_154_Grayscale4_T8 display(EPD_DC, EPD_RESET, EPD_CS, SRAM_CS, EPD_BUSY);
 //ThinkInk_213_Grayscale4_T5 display(EPD_DC, EPD_RESET, EPD_CS, SRAM_CS, EPD_BUSY);