Require Chef 13 or later

This allows use to use the description field
Signed-off-by: Tim Smith <tsmith@chef.io>

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://travis-ci.org/chef-cookbooks/yum.svg?branch=master)](http://travis-ci.org/chef-cookbooks/yum) [![Cookbook Version](https://img.shields.io/cookbook/v/yum.svg)](https://supermarket.chef.io/cookbooks/yum)
 
-The Yum cookbook exposes the `yum_globalconfig` resource which allows a user to control global yum behavior. This resources aims to allow the user to configure all options listed in the `yum.conf` man page, found at <http://linux.die.net/man/5/yum.conf>
+The Yum cookbook exposes the `yum_globalconfig` resource which allows a user to control global yum behavior. This resources aims to allow the user to configure all options listed in the `yum.conf` man page, found at <http://man7.org/linux/man-pages/man5/yum.conf.5.html>
 
 ## Requirements
 
@@ -13,7 +13,7 @@ The Yum cookbook exposes the `yum_globalconfig` resource which allows a user to
 
 ### Chef
 
-- Chef 12.14+
+- Chef 13+
 
 ### Cookbooks
 

metadata.rb

@@ -11,4 +11,4 @@ end
 
 source_url 'https://github.com/chef-cookbooks/yum'
 issues_url 'https://github.com/chef-cookbooks/yum/issues'
-chef_version '>= 12.15'
+chef_version '>= 13'