bpo-40968: Send http/1.1 ALPN extension (#20959)

Signed-off-by: Christian Heimes <christian@python.org>
diff --git a/Doc/library/http.client.rst b/Doc/library/http.client.rst
index 35997db..56f4c0a 100644
--- a/Doc/library/http.client.rst
+++ b/Doc/library/http.client.rst
@@ -99,6 +99,11 @@
       :attr:`ssl.SSLContext.post_handshake_auth` for the default *context* or
       when *cert_file* is passed with a custom *context*.
 
+   .. versionchanged:: 3.10
+      This class now sends an ALPN extension with protocol indicator
+      ``http/1.1`` when no *context* is given. Custom *context* should set
+      ALPN protocols with :meth:`~ssl.SSLContext.set_alpn_protocol`.
+
    .. deprecated:: 3.6
 
        *key_file* and *cert_file* are deprecated in favor of *context*.
diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index b37f230..b4435a6 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -109,6 +109,11 @@
    .. versionchanged:: 3.4.3
       *context* was added.
 
+   .. versionchanged:: 3.10
+      HTTPS connection now send an ALPN extension with protocol indicator
+      ``http/1.1`` when no *context* is given. Custom *context* should set
+      ALPN protocols with :meth:`~ssl.SSLContext.set_alpn_protocol`.
+
    .. deprecated:: 3.6
 
        *cafile*, *capath* and *cadefault* are deprecated in favor of *context*.