added events

src/diagram.typ

@@ -9,6 +9,15 @@
   ),)
 }
 
+#let _evt(participant, event) = {
+  return ((
+    type: "evt",
+    participant: participant,
+    event: event,
+    lifeline-style: auto
+  ),)
+}
+
 #let diagram(elements) = {
   if elements == none {
     return