docs: Add lastmod to content files

Based on last commit in Git.

docs/content/tutorials/automated-deployments.md

@@ -2,6 +2,7 @@
 authors:
 - Arjen Schwarz
 - Samuel Debruyn
+lastmod: 2015-11-01
 date: 2015-01-12
 linktitle: Automated deployments
 toc: true

docs/content/tutorials/create-a-multilingual-site.md

@@ -1,5 +1,6 @@
 ---
 author: "Rick Cogley"
+lastmod: 2015-12-24
 date: 2015-07-08
 linktitle: Multilingual Site
 menu:

docs/content/tutorials/creating-a-new-theme.md

@@ -1,5 +1,6 @@
 ---
 author: "Michael Henderson"
+lastmod: 2015-12-01
 date: 2015-11-26
 linktitle: Creating a New Theme
 toc: true

docs/content/tutorials/github-pages-blog.md

@@ -2,6 +2,7 @@
 aliases:
     - /tutorials/github_pages_blog/
 author: Spencer Lyon
+lastmod: 2015-12-24
 date: 2014-03-21
 linktitle: Hosting on GitHub
 toc: true

docs/content/tutorials/installing-on-mac.md

@@ -1,5 +1,6 @@
 ---
 author: "Michael Henderson"
+lastmod: 2016-01-04
 date: 2015-02-22
 linktitle: Installing on Mac
 toc: true

docs/content/tutorials/installing-on-windows.md

@@ -1,5 +1,6 @@
 ---
 author: "Michael Henderson"
+lastmod: 2015-12-23
 date: 2015-03-30
 linktitle: Installing on Windows
 toc: true

docs/content/tutorials/mathjax.md

@@ -1,5 +1,6 @@
 ---
 author: Spencer Lyon
+lastmod: 2015-05-22
 date: 2014-03-20
 menu:
   main:

docs/content/tutorials/migrate-from-jekyll.md

@@ -1,4 +1,5 @@
 ---
+lastmod: 2015-12-24
 date: 2014-03-10
 linktitle: Migrating from Jekyll
 toc: true