Add on_raw_thread_update event

docs/api.rst

@@ -1176,7 +1176,11 @@ Threads
 
 .. function:: on_thread_update(before, after)
 
-    Called whenever a thread is updated.
+    Called whenever a thread is updated. If the thread could
+    not be found in the internal cache this event will not be called.
+    Threads will not be in the cache if they are archived.
+
+    If you need this information use :func:`on_raw_thread_update` instead.
 
     This requires :attr:`Intents.guilds` to be enabled.
 
@@ -1224,6 +1228,18 @@ Threads
     :param thread: The thread that got deleted.
     :type thread: :class:`Thread`
 
+.. function:: on_raw_thread_update(payload)
+
+    Called whenever a thread is update. Unlike :func:`on_thread_update` this
+    is called regardless of the thread being in the internal thread cache or not.
+
+    This requires :attr:`Intents.guilds` to be enabled.
+
+    .. versionadded:: 2.0
+
+    :param payload: The raw event payload data.
+    :type payload: :class:`RawThreadUpdateEvent`
+
 .. function:: on_raw_thread_delete(payload)
 
     Called whenever a thread is deleted. Unlike :func:`on_thread_delete` this
@@ -4119,6 +4135,14 @@ RawIntegrationDeleteEvent
 .. autoclass:: RawIntegrationDeleteEvent()
     :members:
 
+RawThreadUpdateEvent
+~~~~~~~~~~~~~~~~~~~~~~
+
+.. attributetable:: RawThreadUpdateEvent
+
+.. autoclass:: RawThreadUpdateEvent()
+    :members:
+
 RawThreadDeleteEvent
 ~~~~~~~~~~~~~~~~~~~~~~