Add cross-references to the glossary entry for file objects.
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index ad61377..0bb6f3a 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -853,10 +853,10 @@
stdout
stderr
- File objects corresponding to the interpreter's standard input, output and error
- streams. ``stdin`` is used for all interpreter input except for scripts but
- including calls to :func:`input`. ``stdout`` is used for
- the output of :func:`print` and :term:`expression` statements and for the
+ :term:`File objects <file object>` corresponding to the interpreter's standard
+ input, output and error streams. ``stdin`` is used for all interpreter input
+ except for scripts but including calls to :func:`input`. ``stdout`` is used
+ for the output of :func:`print` and :term:`expression` statements and for the
prompts of :func:`input`. The interpreter's own prompts
and (almost all of) its error messages go to ``stderr``. ``stdout`` and
``stderr`` needn't be built-in file objects: any object is acceptable as long