chore: updated hint msg

README.md

@@ -1,4 +1,4 @@
-use:
+usage:
 
 ```console
 cargo build --release

src/main.rs

@@ -9,7 +9,7 @@ mod helpers;
 async fn main() -> Result<()> {
     let args: Vec<String> = std::env::args().collect();
     if args.len() < 2 {
-        eprintln!("Usage: pixiv_download <URL>");
+        eprintln!("Usage: lonefire <URL>\nBTW, lonefire can't download GIF image");
         std::process::exit(1);
     }
     let artwork_url = &args[1];