Update README.md

Updated to include a link to the example image and a link to the source thread.

"Fixes" #4

README.md

@@ -15,6 +15,8 @@ I should note that like others, I initially had trouble reading the sensor data
 > 
 > I used a 2N3906 and following the circuit as described in the PDF; I can now read sensor values from the Roomba!
 
+The D1 mini is small enough to fit into the compartment by the wheel. The [example image of D1 mini inside Roomba compartment](https://community-home-assistant-assets.s3.dualstack.us-west-2.amazonaws.com/optimized/2X/a/a258c7253f8bd3fe76ad9e7aa1202b60bd113d74_2_496x600.jpg) image is not a photo of mine specifically, but it's useful to see where the components fit inside the Roomba. It was sourced from a [community project thread on the Home Assistant forums](https://community.home-assistant.io/t/add-wifi-to-an-older-roomba/23282).
+
 ## Software Setup/Use
 
 Take a look at the example directory for a fully working example.