Cleanup clippy warnings
Cleanup clippy warnings

Enable clippy::missing_errors_doc

warning: docs for function returning `Result` missing `# Errors` section
   --> src/main.rs:164:5
    |
164 | /     pub fn run(mut self) -> io::Result<i32> {
165 | |         debug!("Running with options: {:#?}", self.options);
166 | |
167 | |         let mut files = Vec::new();
...   |
202 | |         self.print_dirs(dirs, no_files, is_only_dir, exit_status)
203 | |     }
    | |_____^
    |

ogham/exa,ogham/exa