_exit(2) should mention truncation of status

[Jan Schaumann <jschauma%netmeister.org@localhost>]

Hello,

exit(3) and wait(2) both mention that only the least
significant 8 bits of the 'status' argument are
returned to the parent process; _exit(2) does not
mention that.

I'd like to add the following note here (see attached
diff).

Arguments against: _exit(2) references wait(2), so
users could in theory dig into that there and find it
mentioned somewhere a few pages down.

Arguments for: makes it much more obvious; OpenBSD has
similar wording in https://man.openbsd.org/_exit.

Any objections?

-Jan

? ._exit.2.swp
Index: _exit.2
===================================================================
RCS file: /cvsroot/src/lib/libc/sys/_exit.2,v
retrieving revision 1.18
diff -r1.18 _exit.2
32c32
< .Dd April 23, 2002
---
> .Dd October 17, 2022
70a71,74
> (Note that only the least significant 8 bits of
> .Em status
> are preserved and returned to the parent via
> .Xr wait 2 Ns .)