Bump kramdown from 0.13.8 to 2.3.0

Bumps [kramdown](https://github.com/gettalong/kramdown) from 0.13.8 to 2.3.0.
- [Release notes](https://github.com/gettalong/kramdown/releases)
- [Changelog](https://github.com/gettalong/kramdown/blob/master/doc/news.page)
- [Commits](https://github.com/gettalong/kramdown/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile

@@ -2,7 +2,7 @@ source "http://rubygems.org"
 
 gem 'builder'
 gem 'coderay'
-gem 'kramdown', '~> 0.13.2'
+gem 'kramdown', '~> 2.3.0'
 gem 'mime-types', '~> 1.16'
 gem 'nanoc', '~> 3.7.3'
 gem 'nokogiri'

Gemfile.lock

@@ -7,7 +7,8 @@ GEM
     coderay (1.1.2)
     cri (2.15.9)
     fssm (0.2.10)
-    kramdown (0.13.8)
+    kramdown (2.3.0)
+      rexml
     mime-types (1.25.1)
     mini_portile2 (2.4.0)
     multi_json (1.14.1)
@@ -19,6 +20,7 @@ GEM
       multi_json (>= 1.0.0)
     rack (2.0.8)
     rake (12.3.3)
+    rexml (3.2.4)
     yajl-ruby (1.4.1)
 
 PLATFORMS
@@ -29,7 +31,7 @@ DEPENDENCIES
   builder
   coderay
   fssm
-  kramdown (~> 0.13.2)
+  kramdown (~> 2.3.0)
   mime-types (~> 1.16)
   nanoc (~> 3.7.3)
   nokogiri