vis: allow boolean :set options to be toggled

Boolean options can be toggled by appending `!` to the option name.

Close #435

1 files changed, 3 insertions, 0 deletions

diff --git a/man/vis.1 b/man/vis.1
index 76cfdfc..b41e45a 100644
--- a/man/vis.1
+++ b/man/vis.1
@@ -1064,6 +1064,9 @@ to change the editor's behavior using the
 command.
 This section describes the options, their abbreviations and their
 default values.
+Boolean options can be toggled by appending
+.Sy "!"
+to the option name.
 .Pp
 In each entry below, the first part of the tag line is the full name
 of the option, followed by any equivalent abbreviations.