update comments

src/main.rs

@@ -127,6 +127,7 @@ fn gemini(
     match storage::Item::from_url(gemini.url.as_str(), &argument.directory) {
         Ok(item) => {
             let mut read: usize = 0;
+            // send header
             match stream.write_all(
                 &response::success::Default {
                     mime: item.mime,
@@ -134,6 +135,7 @@ fn gemini(
                 }
                 .into_bytes(),
             ) {
+                // chunk begin
                 Ok(()) => loop {
                     let mut data = vec![0; argument.chunk];
                     match item.file.read_at(&mut data, read as u64) {