Toggle table of contents via front matter (#1310)

* Add jekyll-toc include
* Reduce whitespace generated by comments
* Add table of contents include to `single` layout
* Replace `toc` include with jekyll-toc enabled YAML Front Matter
* Update README
* Update table of contents documentation
  - Revise `toc` helper include to mention that it will be deprecated in the next major version.
  - Add documentation to `single` layout explaining how to enable table of contents on those pages.
* Update CHANGELOG and history
* Update LICENSE

Close #1222

docs/_docs/10-layouts.md

@@ -7,11 +7,12 @@ single_layout_gallery:
     alt: "single layout with header example"
   - image_path: /assets/images/mm-layout-single-meta.png
     alt: "single layout with comments and related posts"
-last_modified_at: 2017-07-05T15:41:36-04:00
+last_modified_at: 2017-10-20T14:26:10-04:00
+toc: true
+toc_label: "Included Layouts"
+toc_icon: "columns"
 ---
 
-{% include toc icon="columns" title="Included Layouts" %}
-
 The bread and butter of any theme. Below you'll find the layouts included with Minimal Mistakes, what they look like and the type of content they've been built for.
 
 ## Default Layout
@@ -83,6 +84,28 @@ The layout you'll likely use the most --- sidebar and main content combo.
 
 Assign with `layout: single`, or better yet apply as a [Front Matter default]({{ "/docs/configuration/#front-matter-defaults" | absolute_url }}) in `_config.yml`.
 
+### Table of Contents
+
+Auto-generated table of contents list for your posts and pages can be enabled by adding `toc: true` to the YAML Front Matter.
+
+![table of contents example]({{ "/assets/images/mm-toc-helper-example.jpg" | absolute_url }})
+
+| Parameter   | Required | Description | Default |
+| ---------   | -------- | ----------- | ------- |
+| **toc**     | Optional | Show table of contents. (boolean) | `false` |
+| **toc_label** | Optional | Table of contents title. (string) | `toc_label` in UI Text data file. |
+| **toc_icon**  | Optional | Table of contents icon, displays before the title. (string) | [Font Awesome](https://fortawesome.github.io/Font-Awesome/icons/) <i class="fa fa-file-text"></i> **file-text** icon. Any other FA icon can be used instead. |
+
+**TOC example with custom title and icon**
+
+```yaml
+---
+toc: true
+toc_label: "My Table of Contents"
+toc_icon: "gear"
+---
+```
+
 ## Archive Layout
 
 Essentially the same as `single` with markup adjustments and some modules removed.