Add notification model (#488)

Server/models/Notification.js

@@ -0,0 +1,26 @@
+const mongoose = require("mongoose");
+
+const NotificationSchema = mongoose.Schema(
+  {
+    monitorId: {
+      type: mongoose.Schema.Types.ObjectId,
+      ref: "Monitor",
+      immutable: true,
+    },
+    type: {
+      type: String,
+      enum: ["email", "sms"],
+    },
+    address: {
+      type: String,
+    },
+    phone: {
+      type: String,
+    },
+  },
+  {
+    timestamps: true,
+  }
+);
+
+module.exports = mongoose.model("Notification", NotificationSchema);