Fix bug #7617 with documentation of expand-file-name.

 fileio.c (Fexpand_file_name): One more doc fix.

src/ChangeLog

+2010-12-13  Eli Zaretskii  <eliz@gnu.org>
+
+	* fileio.c (Fexpand_file_name): One more doc fix.
+
 2010-12-12  Eli Zaretskii  <eliz@gnu.org>
 
 	* fileio.c (Fexpand_file_name): Doc fix.  (Bug#7617)

src/fileio.c

@@ -828,6 +828,8 @@ DEFUN ("expand-file-name", Fexpand_file_name, Sexpand_file_name, 1, 2, 0,
 Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
 \(does not start with slash or tilde); if DEFAULT-DIRECTORY is nil or missing,
 the current buffer's value of `default-directory' is used.
+NAME should be a string that is a valid file name for the underlying
+filesystem.
 File name components that are `.' are removed, and
 so are file name components followed by `..', along with the `..' itself;
 note that these simplifications are done without checking the resulting