cargo: fix description and homepage

    inherit src;

    meta = with lib; {

      homepage = "http://www.rust-lang.org/";

      homepage = "https://doc.rust-lang.org/cargo/";

      sourceProvenance = with sourceTypes; [ binaryNativeCode ];

      description = "A safe, concurrent, practical language";

      description = "The Rust package manager";

      maintainers = with maintainers; [ qknight ];

      license = [ licenses.mit licenses.asl20 ];

    };