tmux: Use %1 instead of %%

According to the manpage all occurrences of `%1` are replaced, but only
the first of `%%`. The binding also worked with `%%`, but better stick
to the docs.

.config/tmux/tmux.conf

@@ -140,11 +140,11 @@ bind -T copy-mode-vi y \
 	} {
 		command-prompt -k -p (operator-pending) {
 			# do line-wise yank on yy
-			if -F "#{==:%%,y}" {
+			if -F "#{==:%1,y}" {
 				send -X select-line
 			} {
 				send -X begin-selection
-				send "%%"
+				send "%1"
 			}
 			send -X copy-pipe
 		}