module Jekyll::Algolia::FileBrowser

def self.is_404?(file)

rubocop:disable Naming/PredicateName

Source: https://help.github.com/articles/creating-a-custom-404-page-for-your-github-pages-site/
pages. We don't want to index those.
404 pages are not Jekyll defaults but a convention adopted by GitHub

file - The Jekyll file

Public: Check if the file is a 404 error page 
def self.is_404?(file)
  ['404.md', '404.html'].include?(File.basename(file.path))
end