feat: update README.md for ToC

Signed-off-by: Max Wu <jackymaxj@gmail.com>

Author: jackycute

README.md

@@ -13,16 +13,15 @@ Built on [HackMD](https://hackmd.io) source code, CodiMD lets you host and contr
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 # Table of Contents
 
-- [CodiMD](#codimd)
-  - [CodiMD - The Open Source HackMD](#codimd---the-open-source-hackmd)
-  - [Documentation](#documentation)
-    - [Deployment](#deployment)
-    - [Configuration](#configuration)
-    - [Upgrading and Migration](#upgrading-and-migration)
-    - [Developer](#developer)
-  - [Contribution and Discussion](#contribution-and-discussion)
-  - [Browser Support](#browser-support)
-  - [License](#license)
+- [CodiMD - The Open Source HackMD](#codimd---the-open-source-hackmd)
+- [Documentation](#documentation)
+  - [Deployment](#deployment)
+  - [Configuration](#configuration)
+  - [Upgrading and Migration](#upgrading-and-migration)
+  - [Developer](#developer)
+- [Contribution and Discussion](#contribution-and-discussion)
+- [Browser Support](#browser-support)
+- [License](#license)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->