Fix w3mimgdisplay path.

Index: doc/ranger.1
--- doc/ranger.1.orig
+++ doc/ranger.1
@@ -1917,7 +1917,7 @@ docstrings.  Using this will disable the <F1> key on c
 .IP "W3MIMGDISPLAY_PATH" 8
 .IX Item "W3MIMGDISPLAY_PATH"
 By changing this variable, you can change the path of the executable file for
-image previews.  By default, it is set to \fI/usr/lib/w3m/w3mimgdisplay\fR.
+image previews.  By default, it is set to \fI${LOCALBASE}/libexec/w3m/w3mimgdisplay\fR.
 .SH "EXAMPLES"
 .IX Header "EXAMPLES"
 There are various examples on how to extend ranger with plugins or combine