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: d309121592 ("docs: move ext4 administrative docs to admin-guide/")
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/dax.txt

@@ -75,7 +75,7 @@ exposure of uninitialized data through mmap.
 
 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
 
 

Documentation/filesystems/ext2.txt

@@ -358,7 +358,7 @@ and are copied into the filesystem.  If a transaction is incomplete at
 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

MAINTAINERS

@@ -5561,7 +5561,7 @@ W:	http://ext4.wiki.kernel.org
 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)