Update channel create message request size limit (#6092)

* fix: channel create message request size limit

* fix: update max request size in start thread in forum channel

Author: MineBartekSA

docs/resources/Channel.md

@@ -1007,7 +1007,7 @@ Files must be attached using a `multipart/form-data` body as described in [Uploa
 - When sending a message with `tts` (text-to-speech) set to `true`, the current user must have the `SEND_TTS_MESSAGES` permission.
 - When creating a message as a reply to another message, the current user must have the `READ_MESSAGE_HISTORY` permission.
     - The referenced message must exist and cannot be a system message.
-- The maximum request size when sending a message is **8MiB**
+- The maximum request size when sending a message is **25 MiB**
 - For the embed object, you can set every field except `type` (it will be `rich` regardless of if you try to set it), `provider`, `video`, and any `height`, `width`, or `proxy_url` values for images.
 
 ###### JSON/Form Params
@@ -1282,7 +1282,7 @@ Creates a new thread in a forum channel, and sends a message within the created
 - The type of the created thread is `PUBLIC_THREAD`.
 - See [message formatting](#DOCS_REFERENCE/message-formatting) for more information on how to properly format messages.
 - The current user must have the `SEND_MESSAGES` permission (`CREATE_PUBLIC_THREADS` is ignored).
-- The maximum request size when sending a message is **8MiB**.
+- The maximum request size when sending a message is **25 MiB**.
 - For the embed object, you can set every field except `type` (it will be `rich` regardless of if you try to set it), `provider`, `video`, and any `height`, `width`, or `proxy_url` values for images.
 - Examples for file uploads are available in [Uploading Files](#DOCS_REFERENCE/uploading-files).
 - Files must be attached using a `multipart/form-data` body as described in [Uploading Files](#DOCS_REFERENCE/uploading-files).