git: 109330155000 - stable/13 - module(9): Document that evhand can be NULL

The branch stable/13 has been updated by ygy (doc, ports committer):

URL: https://cgit.FreeBSD.org/src/commit/?id=109330155000bfec215ee39148254d2a0b628798

commit 109330155000bfec215ee39148254d2a0b628798
Author:     Felix Johnson <felix.the.red@gmail.com>
AuthorDate: 2021-11-11 06:28:45 +0000
Commit:     Guangyuan Yang <ygy@FreeBSD.org>
CommitDate: 2021-11-14 06:37:20 +0000

    module(9): Document that evhand can be NULL
    
    PR:             192250
    Reported by:    ngie
    
    (cherry picked from commit c5e0492ae81e4b0d7946ccfbedb434a9c4071256)
---
 share/man/man9/module.9 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/share/man/man9/module.9 b/share/man/man9/module.9
index 2ba7b3d6c621..5bd9a13c6925 100644
--- a/share/man/man9/module.9
+++ b/share/man/man9/module.9
@@ -28,7 +28,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 12, 2018
+.Dd November 11, 2021
 .Dt MODULE 9
 .Os
 .Sh NAME
@@ -42,6 +42,9 @@ The structure contains the name of the device, a unique ID number,
 a pointer to an event handler function and to an argument,
 which is given to the event handler,
 as well as some kernel internal data.
+If the event handler function is
+.Dv NULL ,
+the module will use a no-operation function handler instead.
 .Pp
 The
 .Xr DECLARE_MODULE 9