add class04 meta file

classes/class04/meta.json

@@ -0,0 +1,7 @@
+{
+    "name": "Class 04 - Detect Intruders",
+    "id": "class-04",
+    "description": "The fourth class focuses on detecting intruders in your server. Please open the Google document provided to all registered students and follow the document.",
+    "google_doc_url": "",
+    "yt_recording_url": ""
+}