Add missing empty line when appending to existing file

src/main.rs

@@ -127,7 +127,7 @@ async fn main() -> Result<()> {
             Ok(exists) if exists => {
                 debug!("Appending {}", output);
                 let mut file = File::options().append(true).open(&output)?;
-                file.write("\n".as_bytes())?;
+                file.write("\n\n".as_bytes())?;
                 file
             }
             _ => {