Add Series Taxonomy (#19)

Closes #18

content/post/creating-a-new-theme.md

@@ -9,6 +9,7 @@ next: /tutorials/github-pages-blog
 prev: /tutorials/automated-deployments
 title: Creating a New Theme
 weight: 10
+series: Hugo 101
 ---
 
 

content/post/goisforlovers.md

@@ -14,6 +14,7 @@ categories = [
     "golang",
 ]
 menu = "main"
+series = "Hugo 101"
 +++
 
 Hugo uses the excellent [Go][] [html/template][gohtmltemplate] library for

content/post/hugoisforlovers.md

@@ -13,6 +13,7 @@ categories = [
     "golang",
 ]
 menu = "main"
+series = "Hugo 101"
 +++
 
 ## Step 1. Install Hugo

content/post/migrate-from-jekyll.md

@@ -7,6 +7,7 @@ menu:
 prev: /tutorials/mathjax
 title: Migrate to Hugo from Jekyll
 weight: 10
+series: Hugo 101
 ---
 
 ## Move static content to `static`