docs: add easy deployment section to README and installation guide

README.md

@@ -25,6 +25,8 @@ Built with [NestJS framework](https://nestjs.com) and writen in TypeScript. [Pri
 
 Please read the [installation guide](docs/installation.md) to install and run this app.
 
+[![Deploy on Railway](https://railway.com/button.svg)](https://railway.app/template/9Tcyq9?referralCode=ho_K6W)
+
 ## Data
 
 The data we used is based on official sources, managed in [**idn-area-data**](https://github.com/fityannugroho/idn-area-data) repository and distributed as a [npm package](https://www.npmjs.com/package/idn-area-data).

docs/installation.md

@@ -2,13 +2,22 @@
 
 <h2>Table of Content</h2>
 
+- [Easy Deployment](#easy-deployment)
 - [Prerequisite](#prerequisite)
 - [Installation Steps](#installation-steps)
   - [Installation with Docker](#installation-with-docker)
 - [Run the Test](#run-the-test)
 
 ---
 
+## Easy Deployment
+
+You can deploy this app to the cloud with a **single click** using [Railway](https://railway.app). This will set up a new project, create a new PostgreSQL database, and deploy the app.
+
+[![Deploy on Railway](https://railway.com/button.svg)](https://railway.app/template/9Tcyq9?referralCode=ho_K6W)
+
+> After deployment is complete, you need to configure the [Public Networking](https://docs.railway.com/reference/public-networking) to **make your API accessible from the internet**.
+
 ## Prerequisite
 
 - [Node.js](https://nodejs.org/en) (version 18 or higher)