bpo-39507: Add HTTP status 418 "I'm a Teapot" (GH-18291)

diff --git a/Doc/library/http.rst b/Doc/library/http.rst
index f120ada2..14ee733 100644
--- a/Doc/library/http.rst
+++ b/Doc/library/http.rst
@@ -99,6 +99,7 @@
 ``415`` ``UNSUPPORTED_MEDIA_TYPE``          HTTP/1.1 :rfc:`7231`, Section 6.5.13
 ``416`` ``REQUESTED_RANGE_NOT_SATISFIABLE`` HTTP/1.1 Range Requests :rfc:`7233`, Section 4.4
 ``417`` ``EXPECTATION_FAILED``              HTTP/1.1 :rfc:`7231`, Section 6.5.14
+``418`` ``IM_A_TEAPOT``                     HTCPCP/1.0 :rfc:`2324`, Section 2.3.2
 ``421`` ``MISDIRECTED_REQUEST``             HTTP/2 :rfc:`7540`, Section 9.1.2
 ``422`` ``UNPROCESSABLE_ENTITY``            WebDAV :rfc:`4918`, Section 11.2
 ``423`` ``LOCKED``                          WebDAV :rfc:`4918`, Section 11.3
@@ -134,4 +135,4 @@
    Added ``451 UNAVAILABLE_FOR_LEGAL_REASONS`` status code.
 
 .. versionadded:: 3.9
-   Added ``103 EARLY_HINTS`` and ``425 TOO_EARLY`` status codes.
+   Added ``103 EARLY_HINTS``, ``418 IM_A_TEAPOT`` and ``425 TOO_EARLY`` status codes.