Tweak example to make clear the argument is a boolean, not any integer.

With Raymond’s approval.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 1cc4097..439e3bf 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -804,7 +804,7 @@
           >>> d.move_to_end('b')
           >>> ''.join(d.keys)
           'acdeb'
-          >>> d.move_to_end('b', 0)
+          >>> d.move_to_end('b', last=False)
           >>> ''.join(d.keys)
           'bacde'