MAINTAINERS: Add ox11 to FatFs

ox11 is maintaining on FatFs.

Signed-off-by: Nicola Ochsenbein <Nicola.Ochsenbein@husqvarnagroup.com>
diff --git a/MAINTAINERS.yml b/MAINTAINERS.yml
index c038549..a167972 100644
--- a/MAINTAINERS.yml
+++ b/MAINTAINERS.yml
@@ -1371,6 +1371,16 @@
   labels:
     - "area: File System"
 
+"Filesystems: FatFs reentrant support":
+  status: maintained
+  maintainers:
+    - ox11
+  files:
+    - modules/fatfs/zfs_ffsystem.c
+    - tests/subsys/fs/fat_fs_api/src/test_fat_file_reentrant.c
+  labels:
+    - "area: File System"
+
 Formatted Output:
   status: maintained
   maintainers: