Added "version added" to docs
diff --git a/docs/hazmat/primitives/twofactor.rst b/docs/hazmat/primitives/twofactor.rst
index 2b811e1..9d66161 100644
--- a/docs/hazmat/primitives/twofactor.rst
+++ b/docs/hazmat/primitives/twofactor.rst
@@ -15,6 +15,8 @@
.. class:: HOTP(key, length, backend)
+ .. versionadded:: 0.3
+
HOTP objects take a ``key`` and ``length`` parameter. The ``key``
should be randomly generated bytes and is recommended to be 160 bits in
length. The ``length`` parameter controls the length of the generated