pythonGH-96851: Add link to FAQ entry for caching method calls. (pyth…

…onGH-96902)

(cherry picked from commit bbc24b2)

Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>

Doc/faq/programming.rst

@@ -1897,6 +1897,8 @@ The classes can be used like this:
     'blog-why-python-rocks'
 
 
+.. _faq-cache-method-calls:
+
 How do I cache method calls?
 ----------------------------
 

Doc/library/functools.rst

@@ -191,6 +191,9 @@ The :mod:`functools` module defines the following functions:
    The cache keeps references to the arguments and return values until they age
    out of the cache or until the cache is cleared.
 
+   If a method is cached, the `self` instance argument is included in the
+   cache.  See :ref:`faq-cache-method-calls`
+
    An `LRU (least recently used) cache
    <https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(LRU)>`_
    works best when the most recent calls are the best predictors of upcoming