Added tentative styling to first graph.

workshops/image-feature-enhancement.md

 # Image feature enhancement
 
 <img src='https://g.gravizo.com/svg?
- digraph G {
+digraph G {
     shift [fontcolor=white,color=white];
     image -> filter -> "enhanced image";
-    "enhanced image" -> "feature" [label="  aka"];
-    filter -> "feature enhancement" [label=" aka"];   
+    node [shape=box, color=grey, fontcolor=grey];
+    "enhanced image" -> "feature" [label=" aka", style=dashed, color=grey, fontcolor=grey, fontsize=10];
+    node [shape=box, color=grey, fontcolor=grey];
+    filter -> "feature enhancement" [label=" aka", style=dashed, color=grey, fontcolor=grey, fontsize=10];   
 }
 '/>