MAINTAINERS: add hung-task detector section

The hung-task detector is missing in MAINTAINERS.  While it's been quiet
recently, I'm actively working on it and volunteering to review patches. 
Adding this section will make it easier for contributors to know who to
contact.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Lance Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: ioworker0

MAINTAINERS

@@ -11099,6 +11099,14 @@ L:	[email protected]
 S:	Odd Fixes
 F:	drivers/tty/hvc/
 
+HUNG TASK DETECTOR
+M:	Andrew Morton <[email protected]>
+R:	Lance Yang <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	include/linux/hung_task.h
+F:	kernel/hung_task.c
+
 I2C ACPI SUPPORT
 M:	Mika Westerberg <[email protected]>
 L:	[email protected]