deprecate auto-idna on UniformResourceIdentifier (#3832)

* deprecate auto-idna on UniformResourceIdentifier

* fix repr test

* docs

* some updated language
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index ea74846..5b0bcd4 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -1271,15 +1271,26 @@
     .. versionadded:: 0.9
 
     This corresponds to a uniform resource identifier.  For example,
-    ``https://cryptography.io``. The URI is parsed and IDNA decoded (see
-    :rfc:`5895`).
+    ``https://cryptography.io``.
 
-    .. note::
+    ..note::
 
-        URIs that do not contain ``://`` in them will not be decoded.
+        Starting with version 2.1 unicode input is deprecated. If passing an
+        internationalized domain name (IDN) you should first IDNA encode the
+        hostname and then pass the resulting bytes.
+
+    .. attribute:: bytes_value
+
+        .. versionadded:: 2.1
+
+        :type: bytes
 
     .. attribute:: value
 
+        .. deprecated:: 2.1
+
+        Deprecated accessor for the idna-decoded value of :attr:`bytes_value`
+
         :type: :term:`text`
 
 .. class:: IPAddress(value)