docs: allow-passthrough must be set to on to prevent tmux from forwarding the real terminal's response to the inactive pane

sxyazi/yazi#2052

Author: sxyazi

docs/image-preview.md

@@ -51,7 +51,7 @@ it will automatically use the "Window system protocol" to display images - this
 To enable Yazi's image preview to work correctly in tmux, add the following 3 options to your `tmux.conf`:
 
 ```sh
-set -g allow-passthrough all
+set -g allow-passthrough on
 set -ga update-environment TERM
 set -ga update-environment TERM_PROGRAM
 ```