docs: ABI: fix a typo when pointing to w1-generic.rst

There's a typo there:

	w1_generic.rst -> w1-generic.rst

Causing the document reference to point to the wrong place.

Fixes: e2c94d6f ("w1_therm: adding alarm sysfs entry")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/66b47dd879e8ae38b6db6d2f38780e00a29fc086.1592895969.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/ABI/testing/sysfs-driver-w1_therm

@@ -8,7 +8,7 @@ Description:
 		to device min/max capabilities. Values are integer as they are
 		stored in a 8bit register in the device. Lowest value is
 		automatically put to TL. Once set, alarms could be search at
-		master level, refer to Documentation/w1/w1_generic.rst for
+		master level, refer to Documentation/w1/w1-generic.rst for
 		detailed information
 Users:		any user space application which wants to communicate with
 		w1_term device