add Return to Ritherdon Project Overview .dot file.

This is the file used to generate the .png  version of the file in the
main README.md file.

attachments/return-to-ritherdon-project-overview.dot

@@ -0,0 +1,29 @@
+digraph overview {
+	fontname = Arial;
+	node [fontname = Arial];
+	label = "Return to Ritherdon";
+	labelloc = top;
+	style = filled;
+	color = lightgrey;
+	fontsize = 20;
+	subgraph cluster0 {
+		style = filled;
+		node [style = filled, color = white];
+		color = lightblue;
+		label = "Personal Flash in Real-Time (I.E. 'Artwork 1')";
+		fontsize = 16;
+		Light;
+		Midpoint;
+		Relay;
+	}
+	subgraph cluster1 {
+		label = "The other artworks in the exhibiton/project...";
+		fontsize = 16;
+		color = white;
+		style = filled;
+		a5 [label = "Artwork 5"];		
+		a4 [label = "Artwork 4"];
+		a3 [label = "Artwork 3"];
+		a2 [label = "Artwork 2"];
+	}
+}