ABI: sysfs-class-bdi: use What: to describe each property

Instead of listing all bdi entries inside the description, add
one entry for each, just like the remaining ABI files.

That allows get_abi.pl script to properly parse it.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/77e5904dfd275ed2670cd13779e5ef1da96e355c.1632750608.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-class-bdi

@@ -23,14 +23,17 @@ default
 	The default backing dev, used for non-block device backed
 	filesystems which do not provide their own BDI.
 
-Files under /sys/class/bdi/<bdi>/
-
-read_ahead_kb (read-write)
-
+What:		/sys/class/bdi/<bdi>/read_ahead_kb
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
 	Size of the read-ahead window in kilobytes
 
-min_ratio (read-write)
-
+	(read-write)
+What:		/sys/class/bdi/<bdi>/min_ratio
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
 	Under normal circumstances each device is given a part of the
 	total write-back cache that relates to its current average
 	writeout speed in relation to the other devices.
@@ -39,8 +42,12 @@ min_ratio (read-write)
 	percentage of the write-back cache to a particular device.
 	For example, this is useful for providing a minimum QoS.
 
-max_ratio (read-write)
+	(read-write)
 
+What:		/sys/class/bdi/<bdi>/max_ratio
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
 	Allows limiting a particular device to use not more than the
 	given percentage of the write-back cache.  This is useful in
 	situations where we want to avoid one device taking all or
@@ -48,7 +55,12 @@ max_ratio (read-write)
 	mount that is prone to get stuck, or a FUSE mount which cannot
 	be trusted to play fair.
 
-stable_pages_required (read-only)
-
+	(read-write)
+What:		/sys/class/bdi/<bdi>/stable_pages_required
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
 	If set, the backing device requires that all pages comprising a write
 	request must not be changed until writeout is complete.
+
+	(read-only)