feat(Countries): Adding countries endpoint

lib/Models/cities.model.js

@@ -0,0 +1,11 @@
+const mongoose = require('mongoose');
+const { Schema } = mongoose;
+
+const schema = new Schema({
+    country_name: { type: String },
+    country_code: { type: String },
+    state_name: { type: String },
+    city_name: { type: String, required: true }
+});
+
+module.exports = mongoose.model( "cities", schema );