Update 2 files

- /Gemfile
- /_layouts/post.html

Gemfile

@@ -9,6 +9,7 @@ group :jekyll_plugins do
   gem "jekyll-include-cache", "~> 0.2.1"
   gem "jekyll-readme-index", "~> 0.3.0"
   gem "jekyll-default-layout", "~> 0.1.5"
+  gem "jekyll-titles-from-headings", "~> 0.5.3"
   gem "jekyll-theme-minimal"
   gem "jekyll-paginate", "~> 1.1.0"
   gem "kramdown-parser-gfm", "~> 1.1.0"