start locally:

bundle exec jekyll serve

syntax:

comparison-slider (should use ordinary quotes on filepaths):

1. first_image_description and second_image_description is not required (by default its Before/After)
2. description by default is true (do not use quotas)

{%
  include comparison-slider.html
  first_image='assets/images/filename.png'
  second_image='assets/images/filename2.png'
  description=false
  first_image_description='hello'
  second_image_description='hey'
%}