fixed typo

Author: siddacious

README.rst

@@ -67,12 +67,12 @@ Usage Example
     mcp4728.channel_a.value = 65535 # Voltage = VDD
     mcp4728.channel_b.value = int(65535/2) # VDD/2
     mcp4728.channel_c.value = int(65535/4) # VDD/4
-
-    mcp4728.channel_d.value = int(65535/4) # Vref.INTERNAL/4 * 2 => 2.048/4 * 2 = 2.048/2 =  ~ 1.024V
+    mcp4728.channel_d.value = 0 # 0V
 
 
     mcp4728.save_settings() # save the current values to the eeprom,making them the default on power up
 
+
 Contributing
 ============