arduinouno: add schema to at28wr recipe

recipes/arduinouno/at28.md

@@ -14,7 +14,7 @@ to be driven from an Arduino Uno.
 
 ## Schema
 
-(there will soon be an image here, but I have yet to scan my schema)
+![Schema](at28wr.jpg)
 
 This is a rather simple circuit which uses 2 chained '164 shift register to
 drive the AT28 address pins and connects CE, WE, OE and the data pins directly