Customize usage message of cmd
diff --git a/cmd/src/main.rs b/cmd/src/main.rs
index c0b4cc4..26b6ef6 100644
--- a/cmd/src/main.rs
+++ b/cmd/src/main.rs
@@ -7,7 +7,17 @@
use structopt::StructOpt;
#[derive(StructOpt, Debug)]
-#[structopt(name = "cxxbridge", author)]
+#[structopt(
+ name = "cxxbridge",
+ author,
+ about = "https://github.com/dtolnay/cxx",
+ usage = "\
+ cxxbridge <input>.rs Emit .cc file for bridge to stdout
+ cxxbridge <input>.rs --header Emit .h file for bridge to stdout
+ cxxbridge --header Emit cxxbridge.h header to stdout",
+ help_message = "Print help information",
+ version_message = "Print version information"
+)]
struct Opt {
/// Input Rust source file containing #[cxx::bridge]
#[structopt(parse(from_os_str), required_unless = "header")]