doc: clarify fs.StatFs bsize unit

AtCloudDiwash · AtCloudDiwash · commit 26a3c146eabe · 2025-08-08T10:36:27.000-05:00
diff --git a/doc/api/fs.md b/doc/api/fs.md
@@ -7672,7 +7672,7 @@ added:
 
 * Type: {number|bigint}
 
-Optimal transfer block size.
+Optimal transfer block size in bytes.
 
 #### `statfs.ffree`
 
