add versionadded to AsymmetricPadding
diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index c0ddd79..e4ae3e9 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -260,7 +260,7 @@
 
 .. class:: AsymmetricPadding
 
-    A named asymmetric padding.
+    .. versionadded:: 0.2
 
     .. attribute:: name