Update README doc

Author: mzlogin

README.md

@@ -1,33 +1,35 @@
 # vim-markdown-toc
 
-A vim plugin to generate table of contents for a markdown file.
+A vim plugin to generate table of contents for Markdown files.
 
 [中文版使用指南][7]
 
 ## Table of Contents
 
-* [Usage](#usage)
+<!-- vim-markdown-toc GFM -->
+* [Features](#features)
 * [Installation](#installation)
+* [Usage](#usage)
+	* [Generate table of contents](#generate-table-of-contents)
+	* [Update existing table of contents manually](#update-existing-table-of-contents-manually)
+* [Options](#options)
 * [Screenshots](#screenshots)
 * [References](#references)
 
-## Usage
+<!-- vim-markdown-toc -->
 
-There are *GFM* and *Redcarpet* two styles TOC links, see [here][1] to view their difference.
+## Features
 
-Move the cursor to the place you want to insert TOC, then type a command below suit you. The command will generate **headings after the cursor** into TOC.
+* Generate table of contents for Markdown files.
 
-1. `:GenTocGFM`
+  Supported Markdown parsers:
 
-    Generate table of contents in [GFM][2] link style.
+  - [x] GFM (GitHub Flavored Markdown)
+  - [x] Redcarpet
 
-    Suit markdown files in **GitHub repository**, like `README.md`.
-
-2. `:GenTocRedcarpet`
-
-    Generate table of contents in [Redcarpet][3] link style.
+* Update existing table of contents.
 
-    Suit **Jekyll or anywhere else use Redcarpet as it's markdown parser**.
+* Auto update existing table of contents on save.
 
 ## Installation
 
@@ -43,6 +45,60 @@ Suggest to manage your vim plugins via [Vundle][4] so you can install it simply
 
 3. `:PluginInstall`
 
+Installation with [vim-plug][8] is likeness.
+
+## Usage
+
+### Generate table of contents
+
+Move the cursor to the line you want to append table of contents, then type a command below suit you. The command will generate **headings after the cursor** into table of contents.
+
+1. `:GenTocGFM`
+
+    Generate table of contents in [GFM][2] link style.
+
+    This command is suitable for Markdown files in GitHub repositories, like `README.md`, and Markdown files for GitBook.
+
+2. `:GenTocRedcarpet`
+
+    Generate table of contents in [Redcarpet][3] link style.
+
+    This command is suitable for Jekyll or anywhere else use Redcarpet as its Markdown parser.
+
+You can view [here][1] to know differences between *GFM* and *Redcarpet* style toc links.
+
+### Update existing table of contents manually
+
+Just use `:UpdateToc` command.
+
+## Options
+
+1. `g:vmt_auto_update_on_save`
+
+   default: 1
+
+   This plugin will update existing table of contents on save automatic.
+
+   You can close this feature by add the following line to your vimrc file:
+
+   ```viml
+   let g:vmt_auto_update_on_save = 0
+   ```
+
+2. `g:vmt_dont_insert_fence`
+
+   default: 0
+
+   By default, the `:GenTocXXX` commands will add `<!-- vim-markdown-toc -->` fence to the table of contents, it is designed for feature of auto update table of contents on save, it won't effect what your Markdown file looks like after parse.
+   
+   If you don't like this, you can remove the fence by add the following line to your vimrc file:
+   
+   ```viml
+   let g:vmt_dont_insert_fence = 1
+   ```
+   
+   But then you will lose the convenience of auto update tables of contens on save.
+
 ## Screenshots
 
 * [online demo in English][5]
@@ -62,5 +118,6 @@ Suggest to manage your vim plugins via [Vundle][4] so you can install it simply
 [3]: https://github.com/vmg/redcarpet
 [4]: http://github.com/VundleVim/Vundle.Vim
 [5]: https://github.com/mzlogin/chinese-copywriting-guidelines/blob/Simplified/README.en.md
-[6]: http://mazhuang.org/wiki/chinese-copywriting-guidelines/
+[6]: https://github.com/mzlogin/awesome-adb
 [7]: http://mazhuang.org/2015/12/19/vim-markdown-toc/
+[8]: https://github.com/junegunn/vim-plug