swi(9): remove BUGS section

Most of these globals have been removed, save for clk_intr_event. This
one is appropriate to keep in sys/interrupt.h, despite the fact that it
has only one consumer.

Bump .Dd for this and previous changes.

Reviewed by:	markj
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D36939

share/man/man9/swi.9

@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 25, 2020
+.Dd October 12, 2022
 .Dt SWI 9
 .Os
 .Sh NAME
@@ -231,7 +231,3 @@ The
 .Fn swi_remove
 function first appeared in
 .Fx 6.1 .
-.Sh BUGS
-Most of the global variables described in this manual page should not be
-global, or at the very least should not be declared in
-.In sys/interrupt.h .