enquote crate docs

This Rust library quotes, unquotes, and unescapes strings.

Example

```rust extern crate enquote;

fn main() { asserteq!(enquote::enquote('\'', "foo'bar"), "'foo\'bar'"); asserteq!(enquote::unquote("'foo\'bar\n'"), "foo'bar\n"); assert_eq!(enquote::unescape("\n", None), "\n"); } ```