Reword the doc as versionadded.

Doc/library/zipfile.rst

@@ -79,11 +79,10 @@ The module defines the following items:
    of the last modification to the file; the fields are described in section
    :ref:`zipinfo-objects`.
 
-   .. versionchanged:: 3.13
-      While the internals of a :class:`!ZipInfo` objects remain
-      un(der)documented, the ``.compress_level`` attribute was renamed from
-      ``._compresslevel``. The old name continues to work as a property for
-      backwards compatibility.
+   .. versionadded:: 3.13
+      A public ``.compress_level`` attribute has been added to expose the
+      formerly protected ``._compresslevel``.  The older protected name
+      continues to work as a property for backwards compatibility.
 
 .. function:: is_zipfile(filename)