readlink: improve one-line summary: prints canonical file names, too

* src/readlink.c (usage): Adjust one-line summary.
* man/readlink.x: Likewise.
Suggested by Kamil Dudka.

man/readlink.x

@@ -1,5 +1,5 @@
 [NAME]
-readlink \- display value of a symbolic link
+readlink \- print value of a symbolic link or canonical file name
 [DESCRIPTION]
 .\" Add any additional description here
 [SEE ALSO]

src/readlink.c

@@ -61,7 +61,7 @@ usage (int status)
   else
     {
       printf (_("Usage: %s [OPTION]... FILE\n"), program_name);
-      fputs (_("Display value of a symbolic link on standard output.\n\n"),
+      fputs (_("Print value of a symbolic link or canonical file name\n\n"),
 	     stdout);
       fputs (_("\
   -f, --canonicalize            canonicalize by following every symlink in\n\