Add simple 'about' text

src/cli.rs

@@ -85,6 +85,7 @@ impl clap::Args for Negations {
 #[command(
     name = "fd",
     version,
+    about = "A program to find entries in your filesystem",
     after_long_help = "Bugs can be reported on GitHub: https://github.com/sharkdp/fd/issues",
     args_override_self = true,
     group(ArgGroup::new("execs").args(&["exec", "exec_batch", "list_details"]).conflicts_with_all(&[