Update docs and changelog for URI, RFC822Name, and DNSName (#3955)

* Update docs and changelog for URI, RFC822Name, and DNSName

As of 2.1 we want users to pass A-label strings, but we still accept
U-label strings and auto-encode on their behalf (with a deprecation
warning). However, we do not return U-label in the value attribute so
we are making a backwards incompatible change for users that utilize
internationalized domain names.

* language updates

* add presentational to the word list

* the linux dictionary is pathetic

3 files changed, 44 insertions, 57 deletions

diff --git a/docs/glossary.rst b/docs/glossary.rst
index df327605..ce08dbaa 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -94,5 +94,10 @@ Glossary
         bit key, you can calculate the number of bytes by dividing by 8. 128
         divided by 8 is 16, so a 128 bit key is a 16 byte key.
 
+    U-label
+        The presentational unicode form of an internationalized domain
+        name. U-labels use unicode characters outside the ASCII range and
+        are encoded as A-labels when stored in certificates.
+
 .. _`hardware security module`: https://en.wikipedia.org/wiki/Hardware_security_module
 .. _`idna`: https://pypi.org/project/idna/
diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
index f0cfc88e..c53cc80f 100644
--- a/docs/spelling_wordlist.txt
+++ b/docs/spelling_wordlist.txt
@@ -24,6 +24,7 @@ decrypt
 Decrypts
 decrypted
 decrypting
+deprecations
 DER
 deserialize
 deserialized
@@ -74,6 +75,7 @@ plaintext
 pre
 preprocessor
 preprocessors
+presentational
 pseudorandom
 pyOpenSSL
 relicensed
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index 238a24e5..014d1f47 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -1242,66 +1242,53 @@ General Name Classes
 
     .. versionadded:: 0.9
 
-    ..note::
+    .. versionchanged:: 2.1
 
-        Starting with version 2.1 unicode input is deprecated. If passing an
-        email address containing an internationalized domain name (IDN) you
-        should first IDNA encode the hostname and then pass the resulting
-        bytes.
+    .. warning::
 
-    This corresponds to an email address. For example, ``user@example.com``.
-
-    :param bytes value: The email address. If the address contains an
-        internationalized domain name then it must be encoded to an
-        :term:`A-label` before being passed.
+        Starting with version 2.1 :term:`U-label` input is deprecated. If
+        passing an internationalized domain name (IDN) you should first IDNA
+        encode the value and then pass the result as a string. Accessing
+        ``value`` will return the :term:`A-label` encoded form even if you pass
+        a U-label. This breaks backwards compatibility, but only for
+        internationalized domain names.
 
-    .. attribute:: bytes_value
 
-        .. versionadded:: 2.1
-
-        :type: bytes
+    This corresponds to an email address. For example, ``user@example.com``.
 
-        The value as a byte string. This will contain an :term:`A-label` if
-        the domain in the address is an internationalized domain name.
+    :param value: The email address. If the address contains an
+        internationalized domain name then it must be encoded to an
+        :term:`A-label` string before being passed.
 
     .. attribute:: value
 
-        .. deprecated:: 2.1
-
-        Deprecated accessor for the idna-decoded value of :attr:`bytes_value`
-
         :type: :term:`text`
 
 .. class:: DNSName(value)
 
     .. versionadded:: 0.9
 
-    ..note::
+    .. versionchanged:: 2.1
 
-        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.
+    .. warning::
 
-    This corresponds to a domain name. For example, ``cryptography.io``.
+        Starting with version 2.1 :term:`U-label` input is deprecated. If
+        passing an internationalized domain name (IDN) you should first IDNA
+        encode the value and then pass the result as a string. Accessing
+        ``value`` will return the :term:`A-label` encoded form even if you pass
+        a U-label. This breaks backwards compatibility, but only for
+        internationalized domain names.
 
-    :param bytes value: The domain name. If it is an internationalized domain
-        name then it must be encoded to an :term:`A-label` before being passed.
-
-    .. attribute:: bytes_value
-
-        .. versionadded:: 2.1
+    This corresponds to a domain name. For example, ``cryptography.io``.
 
-        :type: bytes
+    :param value: The domain name. If it is an internationalized domain
+        name then it must be encoded to an :term:`A-label` string before being
+        passed.
 
-        The value as a byte string. This will contain an :term:`A-label` if
-        it is an internationalized domain name.
+        :type: :term:`text`
 
     .. attribute:: value
 
-        .. deprecated:: 2.1
-
-        Deprecated accessor for the idna-decoded value of :attr:`bytes_value`
-
         :type: :term:`text`
 
 .. class:: DirectoryName(value)
@@ -1318,33 +1305,26 @@ General Name Classes
 
     .. versionadded:: 0.9
 
-    ..note::
+    .. versionchanged:: 2.1
+
+    .. warning::
 
-        Starting with version 2.1 unicode input is deprecated. If passing an
-        internationalized domain name (IDN) within the URI you should first
-        IDNA encode the hostname and then pass the resulting bytes.
+        Starting with version 2.1 :term:`U-label` input is deprecated. If
+        passing an internationalized domain name (IDN) you should first IDNA
+        encode the value and then pass the result as a string. Accessing
+        ``value`` will return the :term:`A-label` encoded form even if you pass
+        a U-label. This breaks backwards compatibility, but only for
+        internationalized domain names.
 
     This corresponds to a uniform resource identifier.  For example,
     ``https://cryptography.io``.
 
-    :param bytes value: The URI. If it contains an internationalized domain
-        name then it must be encoded to an :term:`A-label` before being passed.
-
-    .. attribute:: bytes_value
-
-        .. versionadded:: 2.1
-
-        :type: bytes
-
-        The value as a byte string. This will contain an :term:`A-label` if
-        the URI contains an internationalized domain name.
+    :param value: The URI. If it contains an internationalized domain
+        name then it must be encoded to an :term:`A-label` string before
+        being passed.
 
     .. attribute:: value
 
-        .. deprecated:: 2.1
-
-        Deprecated accessor for the idna-decoded value of :attr:`bytes_value`
-
         :type: :term:`text`
 
 .. class:: IPAddress(value)