updated readme

Author: olaitanade

README.md

@@ -1,2 +1,52 @@
-# paystack-transaction-charges-to-cus-js
-Pass Paystack Transaction Charges To Customers JS Library
+# PASS PAYSTACK TRANSACTION CHARGE TO CUSTOMER
+
+PaystackTransactionChargeToCustomer provides the implementation to the formula provided by the Paystack support team as regards passing the Paystack transaction charge to customers [Here's the article](https://support.paystack.com/hc/en-us/articles/360009973579-Can-I-pass-the-transaction-charges-to-my-customers-) . 
+
+## Before getting started
+This library currently only works with the Nigerian Paystack Charges
+
+**Flat Fee - 100 Naira**
+ | 
+**Decimal Fee - 1.5%**
+
+### Get Started
+This library would help you calculate the total amount to charge the customer including the Paystack charges. All you need to do is ...
+
+[![Version](https://img.shields.io/npm/v/paystack-transaction-charges-to-cus.svg)](https://www.npmjs.com/package/paystack-transaction-charges-to-cus)
+[![Downloads](https://img.shields.io/npm/dm/paystack-transaction-charges-to-cus.svg)](https://www.npmjs.com/package/mathjs)
+[![Build Status](https://github.com/josdejong/mathjs/workflows/Node.js%20CI/badge.svg)](https://github.com/josdejong/mathjs/actions)
+[![Maintenance](https://img.shields.io/maintenance/yes/2021.svg)](https://github.com/josdejong/mathjs/graphs/commit-activity)
+
+
+## Usage
+
+paystack-transaction-charges-to-cus.js can be used in both node.js and in the browser.
+
+Install paystack-transaction-charges-to-cus.js using [npm](https://www.npmjs.com/package/paystack-transaction-charges-to-cus):
+
+    npm install paystack-transaction-charges-to-cus
+
+
+
+```js
+import {
+  calculateTotalPrice
+} from 'paystack-transaction-charges-to-cus'
+
+// functions and constants
+calculateTotalPrice(100)                // 101
+
+```
+
+
+#### Constants
+
+|Name                   | Type           | Required            | Default Value       | Description         |
+|-----------------------|----------------|---------------------|---------------------|---------------------|
+|  `DECIMAL_FEE `         | `Double`      | true                |  0.0150               | 
+|  `FEE_CAP `               | `int`       | true                |  2000          | 
+|  `FLAT_FEE`              | `int`       | true                |  100          | 
+
+
+## Done 
+Checkout Paystack [API](https://paystack.com/docs/)