Add ical vocabulary

Author: matthieubosquet

src/vocabulary/ical.ts

@@ -0,0 +1,7 @@
+export const ICAL = {
+  comment: "http://www.w3.org/2002/12/cal/ical#comment",
+  dtend: "http://www.w3.org/2002/12/cal/ical#dtend",
+  dtstart: "http://www.w3.org/2002/12/cal/ical#dtstart",
+  location: "http://www.w3.org/2002/12/cal/ical#location",
+  summary: "http://www.w3.org/2002/12/cal/ical#summary",
+} as const;