Update docs for blog post frontmattr

Author: mattstratton

REFERENCE.md

@@ -3,25 +3,26 @@
 # Table of contents
 <!-- MDTOC maxdepth:6 firsth1:0 numbering:0 flatten:0 bullets:0 updateOnSave:1 -->
 
-[Fields in YYYY-CITY.yml](#fields-in-yyyy-cityyml)
-&emsp;[General Fields](#general-fields)
-&emsp;[Date-related Fields](#date-related-fields)
-&emsp;[Branding Fields](#branding-fields)
-&emsp;[Location Fields](#location-fields)
-&emsp;[Navigation Fields](#navigation-fields)
-&emsp;[Organizer Fields](#organizer-fields)
-&emsp;&emsp;[Team Members](#team-members)
-&emsp;&emsp;[Organizer Emails](#organizer-emails)
-&emsp;[Sponsor fields](#sponsor-fields)
-&emsp;&emsp;[Sponsor Levels](#sponsor-levels)
-&emsp;[Program Fields](#program-fields)
-&emsp;&emsp;[Program Items](#program-items)
-&emsp;&emsp;&emsp;[Program Element Colors](#program-element-colors)
-&emsp;&emsp;[Ignite Fields](#ignite-fields)
-[Pages and Frontmatter](#pages-and-frontmatter)
-&emsp;[General Page Fields](#general-page-fields)
-&emsp;[Talk Page Fields](#talk-page-fields)
-&emsp;[Speaker Page Fields](#speaker-page-fields)
+[Fields in YYYY-CITY.yml](#fields-in-yyyy-cityyml)   
+&emsp;[General Fields](#general-fields)   
+&emsp;[Date-related Fields](#date-related-fields)   
+&emsp;[Branding Fields](#branding-fields)   
+&emsp;[Location Fields](#location-fields)   
+&emsp;[Navigation Fields](#navigation-fields)   
+&emsp;[Organizer Fields](#organizer-fields)   
+&emsp;&emsp;[Team Members](#team-members)   
+&emsp;&emsp;[Organizer Emails](#organizer-emails)   
+&emsp;[Sponsor fields](#sponsor-fields)   
+&emsp;&emsp;[Sponsor Levels](#sponsor-levels)   
+&emsp;[Program Fields](#program-fields)   
+&emsp;&emsp;[Program Items](#program-items)   
+&emsp;&emsp;&emsp;[Program Element Colors](#program-element-colors)   
+&emsp;&emsp;[Ignite Fields](#ignite-fields)   
+[Pages and Frontmatter](#pages-and-frontmatter)   
+&emsp;[General Page Fields](#general-page-fields)   
+&emsp;[Talk Page Fields](#talk-page-fields)   
+&emsp;[Speaker Page Fields](#speaker-page-fields)   
+&emsp;[Blog Post Fields](#blog-post-fields)   
 
 <!-- /MDTOC -->
 
@@ -267,3 +268,12 @@ Pages of the type `speaker` have a few additional frontmatter elements available
 | `linkedin` | No       | Speaker's LinkedIn URL                                                                                                                                                                                     | "https://www.linkedin.com/in/mattstratton/" |
 | `github`   | No       | Speakers' GitHub username.                                                                                                                                                                                 | "mattstratton"                              |
 | `image`    | No       | The image for the speaker. This image is relative to the `static/events/YYYY-CITY/speakers` directory. It can be either .png or .jpg. It must be square, and 300px square, 600px square, or 900px square.  | "matt-stratton.jpg"                         |
+
+### Blog Post Fields
+
+| Field Name      | Required | Description                                                                                                                                                                         | Example                                                                                                                                                                                                                                                                                              |
+|-----------------|----------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `Description`   | No       | The short summary of this post. This is used in various places on the site, as well as for sharing. While it is optional, it is highly recommended to use it. Markdown is allowed.  | "[DevOpsDays Chicago](https://devopsdays.org/events/2016-chicago) took place on August 30th & 31st at Summit West in beautiful downtown Chicago. A sold-out, diverse crowd gathered for keynotes, presentations, lightning talks, and open spaces to learn, discuss, and promote all things DevOps." |
+| `Author`        | No       | The name of the person who wrote the blog post.                                                                                                                                     | "Matt Stratton"                                                                                                                                                                                                                                                                                      |
+| `title`         | Yes      | The title for the blog post.                                                                                                                                                        | "Chicago 2016 In Review"                                                                                                                                                                                                                                                                             |
+| `sharing_image` | No       | The image to use for social sharing. This is a path relative to the `static` directory.                                                                                             | "img/blog/chicago-2016-sharing.jpg"                                                                                                                                                                                                                                                                  |