Add rake convert

Converts HTML text to kramdown in terminal

Author: dshevtsov

Diff for: Rakefile

@@ -81,3 +81,11 @@ task index: %w[init] do
         'algolia',
           '--config=_config.yml,_config.index.yml'
 end
+
+desc 'Convert HTML text to kramdown in your terminal'
+task :convert do
+  puts 'Paste HTML text followed by a new line and press Control-D.'.magenta
+  result = `bin/kramdown --input=html --output=kramdown`
+  puts 'Converted text:'.magenta
+  puts result.bold
+end

Diff for: bin/kramdown

@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application 'kramdown' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+require "pathname"
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../../Gemfile",
+  Pathname.new(__FILE__).realpath)
+
+bundle_binstub = File.expand_path("../bundle", __FILE__)
+
+if File.file?(bundle_binstub)
+  if File.read(bundle_binstub, 300) =~ /This file was generated by Bundler/
+    load(bundle_binstub)
+  else
+    abort("Your `bin/bundle` was not generated by Bundler, so this binstub cannot run.
+Replace `bin/bundle` by running `bundle binstubs bundler --force`, then run this command again.")
+  end
+end
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("kramdown", "kramdown")