add a glossary entry for "view"

Doc/glossary.rst

@@ -498,6 +498,13 @@ Glossary
       object has a type.  An object's type is accessible as its
       :attr:`__class__` attribute or can be retrieved with ``type(obj)``.
 
+   view
+      The objects returned from :meth:`dict.keys`, :meth:`dict.items`, and
+      :meth:`dict.items` are called dictionary views.  They are lazy sequences
+      that will see changes in the underlying dictionary.  To force the
+      dictionary view to become a full list use ``list(dictview)``.  See
+      :ref:`dict-views`.
+
    virtual machine
       A computer defined entirely in software.  Python's virtual machine
       executes the :term:`bytecode` emitted by the bytecode compiler.