add table of content (preview) (#3050)

* add toc (preview)

* remove toc in toc

Signed-off-by: Moni <usmoni@gmail.com>

* fix sublinks

* fix indentation

* remove redundant table links

* update caps and indent

* remove axios

Co-authored-by: Moni <usmoni@gmail.com>
Co-authored-by: Jay <jasonsaayman@gmail.com>

README.md

@@ -10,6 +10,37 @@
 [![code helpers](https://www.codetriage.com/axios/axios/badges/users.svg)](https://www.codetriage.com/axios/axios)
 
 Promise based HTTP client for the browser and node.js
+## Table of Contents
+
+  - [Features](#features)
+  - [Browser Support](#browser-support)
+  - [Installing](#installing)
+  - [Example](#example)
+  - [Axios API](#axios-api)
+  - [Request method aliases](#request-method-aliases)
+  - [Concurrency (Deprecated)](#concurrency-deprecated)
+  - [Creating an instance](#creating-an-instance)
+  - [Instance methods](#instance-methods)
+  - [Request Config](#request-config)
+  - [Response Schema](#response-schema)
+  - [Config Defaults](#config-defaults)
+    - [Global axios defaults](#global-axios-defaults)
+    - [Custom instance defaults](#custom-instance-defaults)
+    - [Config order of precedence](#config-order-of-precedence)
+  - [Interceptors](#interceptors)
+  - [Handling Errors](#handling-errors)
+  - [Cancellation](#cancellation)
+  - [Using application/x-www-form-urlencoded format](#using-applicationx-www-form-urlencoded-format)
+    - [Browser](#browser)
+    - [Node.js](#nodejs)
+      - [Query string](#query-string)
+      - [Form data](#form-data)
+  - [Semver](#semver)
+  - [Promises](#promises)
+  - [TypeScript](#typescript)
+  - [Resources](#resources)
+  - [Credits](#credits)
+  - [License](#license)
 
 ## Features