Add docs to copy subcommand

Co-authored-by: Onè <[email protected]>

src/tool/cli.rs

@@ -61,6 +61,7 @@ impl Cli {
 pub enum Commands {
     #[clap(visible_alias = "gen", short_flag = 'g')]
     Generate(GenerateArgs),
+     /// Copies the code from ??? to your clipboard for pasting on leetcode
     Copy,
 }