give the correct fixer name (closes #21604)
diff --git a/Doc/library/2to3.rst b/Doc/library/2to3.rst
index 1092e6b..6473861 100644
--- a/Doc/library/2to3.rst
+++ b/Doc/library/2to3.rst
@@ -392,7 +392,7 @@
    Replaces use of the :class:`set` constructor with set literals.  This fixer
    is optional.
 
-.. 2to3fixer:: standard_error
+.. 2to3fixer:: standarderror
 
    Renames :exc:`StandardError` to :exc:`Exception`.