support for rss/calendar

package.json

@@ -13,6 +13,7 @@
   },
   "main": "./build/index.js",
   "devDependencies": {
+    "@types/ical": "^0.8.0",
     "@types/jsdom": "^20.0.1",
     "@types/luxon": "^3.3.0",
     "@types/mustache": "^4.2.2",
@@ -25,6 +26,8 @@
     "@doc-utils/jsonschema2markdown": "^0.1.1",
     "@doc-utils/markdown2html": "^0.2.1",
     "glob": "^10.2.3",
+    "ical": "^0.8.0",
+    "ical-generator": "^4.1.0",
     "luxon": "^3.3.0",
     "mustache": "^4.2.0",
     "xmlbuilder2": "^3.1.1",