bpo-42360: Add advice to help avoid pickling issues. (GH-23305) (GH-23429)

Author: miss-islington

Doc/library/collections.rst

@@ -849,6 +849,9 @@ they add the ability to access fields by name instead of position index.
     Named tuple instances do not have per-instance dictionaries, so they are
     lightweight and require no more memory than regular tuples.
 
+    To support pickling, the named tuple class should be assigned to a variable
+    that matches *typename*.
+
     .. versionchanged:: 3.1
        Added support for *rename*.