Update README.md

README.md

@@ -2,13 +2,18 @@
 
 Specificaties van de te beheren producten
 
-```blockdiag
-blockdiag {
-  blockdiag -> generates -> "block-diagrams";
-  blockdiag -> is -> "very easy!";
-
-  blockdiag [color = "greenyellow"];
-  "block-diagrams" [color = "pink"];
-  "very easy!" [color = "orange"];
+```plantuml
+@startuml
+left to right direction
+skinparam packageStyle rectangle
+skinparam monochrome true
+actor customer
+actor clerk
+rectangle checkout {
+  customer -- (checkout)
+  (checkout) .> (payment) : include
+  (help) .> (checkout) : extends
+  (checkout) -- clerk
 }
+@enduml
 ```