Configuring IRBRC to improve the visibility of completion dialog colors

.irbrc

# Make sure you installed reline 0.4.0+
Reline::Face.config(:completion_dialog) do |conf|
  conf.define :default, foreground: :white, background: :blue
  #                                                     ^^^^^ :cyan by default
  conf.define :enhanced, foreground: :white, background: :magenta
  conf.define :scrollbar, foreground: :white, background: :blue
end