Does mpackage has a Readme file?

Property definitions

nitc $ ReadmeMetric :: has_readme
	# Does `mpackage` has a Readme file?
	var has_readme: Bool is lazy do
		var readme_path = self.readme_path
		if readme_path == null then return false
		return readme_path.to_s.file_exists
	end
src/metrics/readme_metrics.nit:190,2--195,4