add SubjectKeyIdentifier.create_from_public_key
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index 61971fe..2ccc527 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -1119,6 +1119,21 @@
 
         The binary value of the identifier.
 
+    .. classmethod:: create_from_public_key(public_key)
+
+        .. versionadded:: 1.0
+
+        Creates a new SubjectKeyIdentifier instance using the public key
+        provided to generate the appropriate digest. This should be the public
+        key that is in the certificate.
+
+        :param public_key: One of
+            :class:`~cryptography.hazmat.primitives.asymmetric.rsa.RSAPublicKey`
+            ,
+            :class:`~cryptography.hazmat.primitives.asymmetric.dsa.DSAPublicKey`
+            , or
+            :class:`~cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePublicKey`.
+
 .. class:: SubjectAlternativeName
 
     .. versionadded:: 0.9