doc: filesystems: fix bad references to nonexistent ext4.rst file

The ext4.rst file does not exist anymore. This patch changes all references
to point to the whole ext4 directory.

Fixes: d3091215921b ("docs: move ext4 administrative docs to admin-guide/")
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index bc393e0..6d2c0d3 100644
--- a/Documentation/filesystems/dax.txt
+++ b/Documentation/filesystems/dax.txt
@@ -75,7 +75,7 @@
 
 These filesystems may be used for inspiration:
 - ext2: see Documentation/filesystems/ext2.txt
-- ext4: see Documentation/filesystems/ext4/ext4.rst
+- ext4: see Documentation/filesystems/ext4/
 - xfs:  see Documentation/filesystems/xfs.txt
 
 
diff --git a/Documentation/filesystems/ext2.txt b/Documentation/filesystems/ext2.txt
index a45c9fc..a19973a 100644
--- a/Documentation/filesystems/ext2.txt
+++ b/Documentation/filesystems/ext2.txt
@@ -358,7 +358,7 @@
 the time of the crash, then there is no guarantee of consistency for
 the blocks in that transaction so they are discarded (which means any
 filesystem changes they represent are also lost).
-Check Documentation/filesystems/ext4/ext4.rst if you want to read more about
+Check Documentation/filesystems/ext4/ if you want to read more about
 ext4 and journaling.
 
 References
diff --git a/MAINTAINERS b/MAINTAINERS
index f485597..a5b9587 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5561,7 +5561,7 @@
 Q:	http://patchwork.ozlabs.org/project/linux-ext4/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
 S:	Maintained
-F:	Documentation/filesystems/ext4/ext4.rst
+F:	Documentation/filesystems/ext4/
 F:	fs/ext4/
 
 Extended Verification Module (EVM)