Update Readme

Author: flexdinesh

README.md

@@ -3,12 +3,76 @@
 [![dependencies Status](https://david-dm.org/flexdinesh/axios-retry-interceptor/status.svg)](https://david-dm.org/flexdinesh/axios-retry-interceptor)
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 
-**To be updated...**
+Configurable Axios Interceptor to retry failed http calls.
 
+## Install
 
-## Why? [![start with why](https://img.shields.io/badge/start%20with-why%3F-brightgreen.svg?style=flat)](http://www.ted.com/talks/simon_sinek_how_great_leaders_inspire_action)
+```
+npm install --save axios-retry-interceptor
+```
 
-**To be updated...**
+## Usage
+
+Import
+```js
+import retryInterceptor from 'axios-retry-interceptor';
+// or
+const retryInterceptor = require('axios-retry-interceptor');
+```
+
+Set the interceptor for your axios instance. Voila! ✨
+```js
+retryInterceptor(axios, {
+  maxAttempts: 3,
+  waitTime: 1000
+});
+
+```
+
+## API
+
+### retryInterceptor(axiosInstance, options)
+
+- axiosInstance - your axios instance
+- options - config for retry interceptor
+
+### Options
+
+#### maxAttempts
+
+Max number of times the interceptor should retry the failed http call.
+
+_Type_: Number
+
+_Default_: 3
+
+_Example_: `maxAttempts: 5`
+
+#### waitTime
+
+Duration between each retry attempt in milliseconds(1s=1000ms).
+
+_Type_: Number
+
+_Default_: 0
+
+_Example_: `waitTime: 3000`
+
+#### statuses
+
+Response statuses for which the interceptor should retry.
+
+Ideally any implementation should retry only 5xx status(server errors) and should not retry 4xx status(client errors). The reason is, if a http call fails with a client error, then the retry call will have the same headers/params and will obviously fail. So **by default all 5xx errors will be retried**. If you want to customize the status for which the retries should be made, use this config.
+
+_Type_: Array
+
+_Default_: []
+
+_Example_: `[500, 501, 401]`
+
+## Author's note
+
+Ideally only idempotent http methods (GET, PUT, DELETE, HEAD, OPTIONS) should be retried on failed http calls. Non-idempotent methods like POST should **NOT** be retried and that's why this library will not permit retry of non-idempotent methods.
 
 ## License