Add the table of contents in README.

README.md

@@ -5,6 +5,20 @@
 [![MELPA Stable](https://stable.melpa.org/packages/doom-modeline-badge.svg)](https://stable.melpa.org/#/doom-modeline)
 [![License](http://img.shields.io/:license-gpl3-blue.svg)](http://www.gnu.org/licenses/gpl-3.0.html)
 
+<!-- markdown-toc start - Don't edit this section. Run M-x markdown-toc-refresh-toc -->
+**Table of Contents**
+
+- [doom-modeline](#doom-modeline)
+    - [Feature](#feature)
+    - [Screenshots](#screenshots)
+    - [Install](#install)
+        - [Manual](#manual)
+        - [Use-package](#use-package)
+    - [Customize](#customize)
+    - [FAQ](#faq)
+
+<!-- markdown-toc end -->
+
 A fancy and fast mode-line inspired by minimalism design.
 
 It's integrated into [Centaur Emacs](https://github.com/seagle0128/.emacs.d), [Doom
@@ -320,10 +334,13 @@ Run `M-x customize-group RET doom-modeline RET` or set the variables.
     (set-face-attribute 'mode-line nil :height 100)
     (set-face-attribute 'mode-line-inactive nil :height 100)
     ```
+
     or
+
     ```emacs-lisp
     (custom-set-faces
       '(mode-line ((t (:height 0.9))))
       '(mode-line-inactive ((t (:height 0.9)))))
     ```
+
     Please refer to [#189](https://github.com/seagle0128/doom-modeline/issues/189).