[FIX] doc: specify correct field name in mail

closes odoo/odoo#30718

addons/mail/models/mail_thread.py

@@ -1796,7 +1796,7 @@ class MailThread(models.AbstractModel):
                 if False/0, mail.message model will also be set as False
             :param str body: body of the message, usually raw HTML that will
                 be sanitized
-            :param str type: see mail_message.type field
+            :param str type: see mail_message.message_type field
             :param str content_subtype:: if plaintext: convert body into html
             :param int parent_id: handle reply to a previous message by adding the
                 parent partners to the message in case of private discussion

doc/reference/mixins.rst

@@ -84,7 +84,7 @@ to manage followers on your record:
     
     :param str body: body of the message, usually raw HTML that will
         be sanitized
-    :param str message_type: see mail_message.type field
+    :param str message_type: see mail_message.message_type field
     :param str content_subtype: if plaintext: convert body into html
     :param int parent_id: handle reply to a previous message by adding the
         parent partners to the message in case of private discussion