add vga schematic

README.md

@@ -46,6 +46,8 @@ Name|Screenshot|Description
 [test_pattern](scanvideo/test_pattern)|![](scanvideo/test_pattern/screenshot.jpg)| Display color bars
 [textmode](scanvideo/textmode)|![](scanvideo/textmode/screenshot.jpg)| Shows off chained DMA to generate scanlines out of glyph fragments via DMA/PIO
 
+The above are intended to be used with the VGA demo board as described in [Hardware Design with RP2040](https://rptl.io/rp2040-design) however it is possible to wire your own VGA output according to the following schematic:
+![](scanvideo/Raspberry Pi Pico to VGA Connection Schematic.png)
 
 ## Sleep