Do not parse filename into String in CLI example

[nagisa]

Content Bug Report

Page(s) Affected

https://www.rust-lang.org/what/cli

What needs to be fixed?

The example that currently reads like this:

/// Read some lines of a file
#[derive(Debug, StructOpt)]
struct Cli {
    /// Input file to read
    file: String,
    /// Number of lines to read
    #[structopt(short = "n")]
    num: usize,
}

Suggested Improvement

file should be PathBuf or OsString.

[tshepang]

I'd go as far as calling the binding path, for I like reserving the name file for the handle itself (let file = File::open...)

[XAMPPRocky]

I'm going to close this as duplicate of #838