Improve specs

- Add test examples for bold and italic content
- Move some test examples
- Adjust RSpec options

Rakefile

@@ -5,7 +5,10 @@ require 'bundler/gem_tasks'
 begin
   require 'rspec/core/rake_task'
 
-  RSpec::Core::RakeTask.new(:spec)
+  RSpec::Core::RakeTask.new(:spec) do |t|
+    # t.ruby_opts = %w[-w]
+    t.rspec_opts = ['--color', '--format documentation']
+  end
 
   task default: :spec
 rescue LoadError