Fix documentation linter

docs/Gemfile

@@ -1,4 +1,7 @@
-source "https://rubygems.org"
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
 # Hello! This is where you manage which Jekyll version is used to run.
 # When you want to use a different version, change it below, save the
 # file and run `bundle install`. Run Jekyll with `bundle exec`, like so:
@@ -7,24 +10,17 @@ source "https://rubygems.org"
 #
 # This will help ensure the proper Jekyll version is running.
 # Happy Jekylling!
-gem "jekyll", "~> 4.0.1"
+gem 'jekyll', '~> 4.0.1'
 # This is the default theme for new Jekyll sites. You may change this to anything you like.
-gem "minima", "~> 2.5"
+gem 'minima', '~> 2.5'
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
 # gem "github-pages", group: :jekyll_plugins
 # If you have any plugins, put them here!
 group :jekyll_plugins do
-  gem "jekyll-feed", "~> 0.12"
-end
-
-# Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem
-# and associated library.
-install_if -> { RUBY_PLATFORM =~ %r!mingw|mswin|java! } do
-  gem "tzinfo", "~> 1.2"
-  gem "tzinfo-data"
+  gem 'github-pages'
+  gem 'jekyll-feed', '~> 0.12'
 end
 
 # Performance-booster for watching directories on Windows
-gem "wdm", "~> 0.1.1", :install_if => Gem.win_platform?
-gem "just-the-docs"
+gem 'just-the-docs'