feat(Countries): Adding countries endpoint

lib/Models/memberships.model.js

@@ -0,0 +1,10 @@
+const mongoose = require('mongoose');
+const { Schema } = mongoose;
+
+const schema = new Schema({
+    name: { type: String, required: true }, // free, pro
+    price: { type: Number },
+    validity : { type: Number }, // number 0f days
+});
+
+module.exports = mongoose.model( "memberships", schema );