Adds a table of contents to the readme and contributing files

  * uses the doctoc utility to easily generate the table of contents

CONTRIBUTING.md

@@ -1,3 +1,16 @@
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+**Table of Contents**  *generated with [DocToc](https://github.com/thlorenz/doctoc)*
+
+- [How to contribute:](#how-to-contribute)
+  - [Bug reports / Issues](#bug-reports--issues)
+  - [Code](#code)
+    - [Commit Messages](#commit-messages)
+    - [About Pull Requests (PR's)](#about-pull-requests-prs)
+  - [Documentation](#documentation)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
 # How to contribute:
 
 ## Bug reports / Issues

README.md

@@ -1,3 +1,33 @@
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+**Table of Contents**  *generated with [DocToc](https://github.com/thlorenz/doctoc)*
+
+- [ActsAsTaggableOn](#actsastaggableon)
+  - [Installation](#installation)
+      - [Post Installation](#post-installation)
+      - [For MySql users](#for-mysql-users)
+  - [Usage](#usage)
+    - [Finding most or least used tags](#finding-most-or-least-used-tags)
+    - [Finding Tagged Objects](#finding-tagged-objects)
+    - [Relationships](#relationships)
+    - [Dynamic Tag Contexts](#dynamic-tag-contexts)
+    - [Tag Parsers](#tag-parsers)
+    - [Tag Ownership](#tag-ownership)
+      - [Working with Owned Tags](#working-with-owned-tags)
+        - [Adding owned tags](#adding-owned-tags)
+        - [Removing owned tags](#removing-owned-tags)
+    - [Dirty objects](#dirty-objects)
+    - [Tag cloud calculations](#tag-cloud-calculations)
+  - [Configuration](#configuration)
+      - [Upgrading](#upgrading)
+  - [Contributors](#contributors)
+  - [Compatibility](#compatibility)
+  - [TODO](#todo)
+  - [Testing](#testing)
+  - [License](#license)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
 # ActsAsTaggableOn
 
 [![Join the chat at https://gitter.im/mbleigh/acts-as-taggable-on](https://badges.gitter.im/mbleigh/acts-as-taggable-on.svg)](https://gitter.im/mbleigh/acts-as-taggable-on?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)