Feature request: Display file names that violate the `exists` rule

[romanstetsyk]

Currently, error messages like . failed for `.*` rules: exists:1 (debug: 10) display only the number of files that violate the rule. It would be nice to have a list of these file names, for example, by adding a --verbose flag, and an error message like "Expected x files but found y: [...list of files...]".