fix(docs): strip current directory prefix

[ryzhak]

Resolves #4533

Right now there's an issue on generating docs which is reproducible in a default forge project:

// works fine
forge doc --out docs 

 // throws "Error: prefix not found"
forge doc --out ./docs

The root cause of the issue is this line. Somehow Path::strip_prefix strips "extra" characters in path, example:

let path_str = "/my/path/./../other1/other2";
let path = Path::new(path_str);
let prefix = "/my/path";
let result = path.strip_prefix(prefix);
println!("<Path> {:?}", result); // <Path> Ok("../other1/other2")

Notice that in the example above the ./ part is also stripped while it was not mentioned in the prefix. Interestingly there is also the String::strip_prefix method which actually works as expected (doesn't strip "extra" characters which can be seen in this rust playground).

What happens here is (roughly) that Path::new("/project/./../project/docs").strip_prefix("/project") returns ../project/docs instead of ./../project/docs which produces the Prefix not found error on subsequent strip_prefix calls.

There're many places where strip_prefix is used (in the forge-doc crate) so I suppose the simplest solution is to remove the ./ prefix from the out option.

Notes:

• probably there's an easier way to achieve the same result via clap arguments
• not sure how it affects windows users

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes