[man] Suggest setting RUNEWIDTH_EASTASIAN to 0 or 1

Close #2389

CHANGELOG.md

@@ -194,7 +194,7 @@ CHANGELOG
 - Added color name `preview-label` for `--preview-label` (defaults to `label`
   for `--border-label`)
 - Better support for (Windows) terminals where each box-drawing character
-  takes 2 columns. Set `RUNEWIDTH_EASTASIAN` environment variable to `1`.
+  takes 2 columns. Set `RUNEWIDTH_EASTASIAN` environment variable to `0` or `1`.
     - On Vim, the variable will be automatically set if `&ambiwidth` is `double`
 - Behavior changes
     - fzf will always execute the preview command if the command template

man/man1/fzf.1

@@ -241,8 +241,9 @@ Draw border around the finder
 .br
 
 If you use a terminal emulator where each box-drawing character takes
-2 columns, try setting \fBRUNEWIDTH_EASTASIAN\fR to \fB1\fR. If the border is
-still not properly rendered, set \fB--no-unicode\fR.
+2 columns, try setting \fBRUNEWIDTH_EASTASIAN\fR environment variable to
+\fB0\fR or \fB1\fR. If the border is still not properly rendered, set
+\fB--no-unicode\fR.
 
 .TP
 .BI "--border-label" [=LABEL]