Added change setting info for SD_CS

README.md

@@ -6,6 +6,7 @@
 ## Parts:
 * Arduino MEGA 2560
 * A [2.8'' TFT LCD shield w/Cap Touch and microSD](https://www.adafruit.com/product/1947)
+(anything that works with ILI9341 should work)
 * A microSD
 
 ## Setup:
@@ -14,5 +15,6 @@
 1. Change your settings in reader.ino
     * `DEBUG`: whether or not to serial print debug messages
     * `BRIGHTNESS`: 0-255 for the backlight strength
+    * `SD_CS`: if the SD card is connected to a different port
 1. Upload the sketch
 1. Explore :)