MAINTAINERS: add myself as maintainer of fs/btrfs

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
diff --git a/MAINTAINERS b/MAINTAINERS
index 9c1543f..b50652b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -527,6 +527,13 @@
 S:	Maintained
 F:	tools/binman/
 
+BTRFS
+M:	Marek Behun <marek.behun@nic.cz>
+S:	Maintained
+F:	cmd/btrfs.c
+F:	fs/btrfs/
+F:	include/btrfs.h
+
 BUILDMAN
 M:	Simon Glass <sjg@chromium.org>
 S:	Maintained