[2.0.x] MKS SBASE - Separate SD_DETECT for LCD and on-board SD cards (#10557)

Marlin/src/config/examples/Mks/Sbase/000-README_RepRap_Discount_Full_Graphic_Smart_Controller.txt

 
 Adafruit 10-pin IDC Socket Rainbow Breakout Cable [1199]
   https://www.adafruit.com/product/1199
+
+
+/////////////////////////////////////////////////////////////////////
+
+27 APR 2018
+
+If you also want a functional SD_DETECT_PIN then you'll need to also move the following pin:
+
+    used to go to P0.27 to J8-5
+
+if you decide to use a different pin then the pins_MKS_SBASE.h file will need to be modified.

Marlin/src/pins/pins_MKS_SBASE.h

   #define BTN_ENC          P1_30   // EXP1.2
   #define BTN_EN1          P3_26   // EXP2.5
   #define BTN_EN2          P3_25   // EXP2.3
-  #define SD_DETECT_PIN    P0_27   // EXP2.7
   #define LCD_PINS_RS      P0_16   // EXP1.4
   #define LCD_SDSS         P0_28   // EXP2.4
   #define LCD_PINS_ENABLE  P0_18   // EXP1.3
 #define MISO_PIN           P1_23   // J8-3 (moved from EXP2 P0.8)
 #define MOSI_PIN           P2_12   // J8-4 (moved from EXP2 P0.5)
 #define SS_PIN             P0_28
-#define SD_DETECT_PIN      P0_27
 #define SDSS               P0_06
 
 /**
+ * P0.27 is on EXP2 and the on-board SD card's socket. That means it can't be
+ * used as the SD_DETECT for the LCD's SD card.
+ *
+ * The best solution is to use the custom cable to connect the LCD's SD_DETECT
+ * to a pin NOT on EXP2.
+ *
+ * If you can't find a pin to use for the LCD's SD_DETECT then comment out
+ * SD_DETECT_PIN entirely and remove that wire from the the custom cable.
+ */
+#define SD_DETECT_PIN      P2_11   // J8-5 (moved from EXP2 P0.27)
+
+
+/**
  *  PWMs
  *
  *  There are 6 PWMs.  Each PWM can be assigned to one of two pins.