man: Add missing doc-operating-system-NetBSD string variable

Fixes: commit 99320b9168ffb0112def1a712e8d59441d1b46d9.

diff --git a/man/vis.3bsd b/man/vis.3bsd
index 00d9ebe8acf9ef0ceb8d8f3a4fa1935efdc31b49..7895af4fd0890145378f85d98f5f8e526eeaaa81 100644 (file)
--- a/man/vis.3bsd
+++ b/man/vis.3bsd
@@ -529,6 +529,7 @@ The destination buffer size is not large enough to perform the conversion.
 .%O "RFC 2045"
 .Re
 .Sh HISTORY
+.ds doc-operating-system-NetBSD-7.0 7.0
 The
 .Fn vis ,
 .Fn strvis ,