(file-name-coding-system, default-file-name-coding-system): Doc fix (links

to referenced variables added).

src/fileio.c

@@ -6111,17 +6111,17 @@ syms_of_fileio ()
 
   DEFVAR_LISP ("file-name-coding-system", &Vfile_name_coding_system,
 	       doc: /* *Coding system for encoding file names.
-If it is nil, default-file-name-coding-system (which see) is used.  */);
+If it is nil, `default-file-name-coding-system' (which see) is used.  */);
   Vfile_name_coding_system = Qnil;
 
   DEFVAR_LISP ("default-file-name-coding-system",
 	       &Vdefault_file_name_coding_system,
 	       doc: /* Default coding system for encoding file names.
-This variable is used only when file-name-coding-system is nil.
+This variable is used only when `file-name-coding-system' is nil.
 
-This variable is set/changed by the command set-language-environment.
+This variable is set/changed by the command `set-language-environment'.
 User should not set this variable manually,
-instead use file-name-coding-system to get a constant encoding
+instead use `file-name-coding-system' to get a constant encoding
 of file names regardless of the current language environment.  */);
   Vdefault_file_name_coding_system = Qnil;