add information about why we deprecated the concrete providers
diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
index f621dbd..160ff18 100644
--- a/docs/hazmat/primitives/asymmetric/rsa.rst
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -287,6 +287,11 @@
Deprecated Concrete Classes
~~~~~~~~~~~~~~~~~~~~~~~~~~~
+These classes were deprecated in version 0.5 in favor of backend specific
+providers of the
+:class:`~cryptography.hazmat.primitives.interfaces.RSAPrivateKey` and
+:class:`~cryptography.hazmat.primitives.interfaces.RSAPublicKey` interfaces.
+
.. class:: RSAPrivateKey(p, q, private_exponent, dmp1, dmq1, iqmp, public_exponent, modulus)
.. versionadded:: 0.2