docs: fix some broken documentation references

Some documentation files received recent changes and are
pointing to wrong places.

Those references can easily fixed with the help of a
script:

	$ ./scripts/documentation-file-ref-check --fix
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.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.txt
+- ext4: see Documentation/filesystems/ext4/ext4.rst
 - 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.txt if you want to read more about
+Check Documentation/filesystems/ext4/ext4.rst if you want to read more about
 ext4 and journaling.
 
 References

MAINTAINERS

@@ -840,7 +840,7 @@ ANALOG DEVICES INC ADGS1408 DRIVER
 M:	Mircea Caprioru <mircea.caprioru@analog.com>
 S:	Supported
 F:	drivers/mux/adgs1408.c
-F:	Documentation/devicetree/bindings/mux/adgs1408.txt
+F:	Documentation/devicetree/bindings/mux/adi,adgs1408.txt
 
 ANALOG DEVICES INC ADP5061 DRIVER
 M:	Stefan Popa <stefan.popa@analog.com>
@@ -5514,7 +5514,7 @@ 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.txt
+F:	Documentation/filesystems/ext4/ext4.rst
 F:	fs/ext4/
 
 Extended Verification Module (EVM)

net/bridge/Kconfig

@@ -17,7 +17,7 @@ config BRIDGE
 	  other third party bridge products.
 
 	  In order to use the Ethernet bridge, you'll need the bridge
-	  configuration tools; see <file:Documentation/networking/bridge.txt>
+	  configuration tools; see <file:Documentation/networking/bridge.rst>
 	  for location. Please read the Bridge mini-HOWTO for more
 	  information.