Fix field name in rom/storage config struct

src/rom.rs

@@ -14,7 +14,7 @@ use crate::{
 
 #[derive(Deserialize)]
 struct Config {
-    file_name: Option<String>,
+    image: Option<String>,
 }
 
 #[derive(Debug)]

src/storage.rs

@@ -16,7 +16,7 @@ const SECTOR_SIZE: usize = 256;
 
 #[derive(Deserialize)]
 struct Config {
-    file_name: Option<String>,
+    image: Option<String>,
 }
 
 #[derive(Debug)]