bpo-40204: Fix reference to terms in the doc (GH-21865)
Sphinx 3 requires to refer to terms with the exact case.
For example, fix the Sphinx 3 warning:
Doc/library/pkgutil.rst:71: WARNING: term Loader not found in case
sensitive match.made a reference to loader instead.
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst
index 685552f..0d780e3 100644
--- a/Doc/tutorial/classes.rst
+++ b/Doc/tutorial/classes.rst
@@ -849,7 +849,7 @@
Generators
==========
-:term:`Generator`\s are a simple and powerful tool for creating iterators. They
+:term:`Generators <generator>` are a simple and powerful tool for creating iterators. They
are written like regular functions but use the :keyword:`yield` statement
whenever they want to return data. Each time :func:`next` is called on it, the
generator resumes where it left off (it remembers all the data values and which