MAINTAINERS: Add entry for closures

closures, from bcache, are async widgets with a variety of uses.
bcachefs also uses them, so they're being moved to lib/; mark them as
maintained.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

MAINTAINERS

@@ -5051,6 +5051,14 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
 F:	Documentation/devicetree/bindings/timer/
 F:	drivers/clocksource/
 
+CLOSURES
+M:	Kent Overstreet <kent.overstreet@linux.dev>
+L:	linux-bcachefs@vger.kernel.org
+S:	Supported
+C:	irc://irc.oftc.net/bcache
+F:	include/linux/closure.h
+F:	lib/closure.c
+
 CMPC ACPI DRIVER
 M:	Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
 M:	Daniel Oliveira Nascimento <don@syst.com.br>