libtool.texi: Update link mode documentation

* doc/libtool.texi: Specify a directory after the '-bindir' option
  when linking.

doc/libtool.texi

diff --git a/doc/libtool.texi b/doc/libtool.texi
index 084fce4..d9f1a22 100644
--- a/doc/libtool.texi
+++ b/doc/libtool.texi
@@ -1515,7 +1515,7 @@
 i.e.@: no version information is stored and no symbolic links are created.
 If the platform requires versioning, this option has no effect.
 
-@item -bindir
+@item -bindir @var{directory}
 Pass the absolute name of the directory for installing executable
 programs (@pxref{Directory Variables, , Directory Variables, standards,
 The GNU Coding Standards}).  @command{libtool} may use this value to