bpo-34118: memoryview, range, and tuple are classes  (GH-17761)

Tag memoryview, range, and tuple as classes, the same as list, etcetera, in
the library manual built-in functions list.
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 5abf978..dc3391f 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -952,7 +952,7 @@
 
 
 .. _func-memoryview:
-.. function:: memoryview(obj)
+.. class:: memoryview(obj)
    :noindex:
 
    Return a "memory view" object created from the given argument.  See
@@ -1408,7 +1408,7 @@
 
 
 .. _func-range:
-.. function:: range(stop)
+.. class:: range(stop)
               range(start, stop[, step])
    :noindex:
 
@@ -1655,7 +1655,7 @@
 
 
 .. _func-tuple:
-.. function:: tuple([iterable])
+.. class:: tuple([iterable])
    :noindex:
 
    Rather than being a function, :class:`tuple` is actually an immutable