OCSP response serialization (#4482)

* support OCSP response serialization

* empty commit, good times
diff --git a/docs/x509/ocsp.rst b/docs/x509/ocsp.rst
index 528502a..499e7a9 100644
--- a/docs/x509/ocsp.rst
+++ b/docs/x509/ocsp.rst
@@ -411,6 +411,14 @@
 
         The extensions encoded in the response.
 
+    .. method:: public_bytes(encoding)
+
+        :param encoding: The encoding to use. Only
+            :attr:`~cryptography.hazmat.primitives.serialization.Encoding.DER`
+            is supported.
+
+        :return bytes: The serialized OCSP response.
+
 .. class:: OCSPResponseStatus
 
     .. versionadded:: 2.4