fix: mark channel name as nullable (#4571)

Author: onerandomusername

docs/resources/Channel.md

@@ -13,7 +13,7 @@ Represents a guild or DM channel within Discord.
 | guild_id?                      | snowflake                                                                  | the id of the guild (may be missing for some channel objects received over gateway guild dispatches)                                                                                            |
 | position?                      | integer                                                                    | sorting position of the channel                                                                                                                                                                 |
 | permission_overwrites?         | array of [overwrite](#DOCS_RESOURCES_CHANNEL/overwrite-object) objects     | explicit permission overwrites for members and roles                                                                                                                                            |
-| name?                          | string                                                                     | the name of the channel (1-100 characters)                                                                                                                                                      |
+| name?                          | ?string                                                                    | the name of the channel (1-100 characters)                                                                                                                                                      |
 | topic?                         | ?string                                                                    | the channel topic (0-1024 characters)                                                                                                                                                           |
 | nsfw?                          | boolean                                                                    | whether the channel is nsfw                                                                                                                                                                     |
 | last_message_id?               | ?snowflake                                                                 | the id of the last message sent in this channel (may not point to an existing or valid message)                                                                                                 |