Add guild member banners

Author: advaith1

docs/resources/Guild.md

@@ -347,6 +347,7 @@ A partial [guild](#DOCS_RESOURCES_GUILD/guild-object) object. Represents an Offl
 | user?                         | [user](#DOCS_RESOURCES_USER/user-object) object                                      | the user this guild member represents                                                                                                                                                                                                |
 | nick?                         | ?string                                                                              | this user's guild nickname                                                                                                                                                                                                           |
 | avatar?                       | ?string                                                                              | the member's [guild avatar hash](#DOCS_REFERENCE/image-formatting)                                                                                                                                                                   |
+| banner?                       | ?string                                                                              | the member's [guild banner hash](#DOCS_REFERENCE/image-formatting)                                                                                                                                                                   |
 | roles                         | array of snowflakes                                                                  | array of [role](#DOCS_TOPICS_PERMISSIONS/role-object) object ids                                                                                                                                                                     |
 | joined_at                     | ISO8601 timestamp                                                                    | when the user joined the guild                                                                                                                                                                                                       |
 | premium_since?                | ?ISO8601 timestamp                                                                   | when the user started [boosting](https://support.discord.com/hc/en-us/articles/360028038352-Server-Boosting-) the guild                                                                                                              |
@@ -371,6 +372,7 @@ A partial [guild](#DOCS_RESOURCES_GUILD/guild-object) object. Represents an Offl
   "user": {},
   "nick": "NOT API SUPPORT",
   "avatar": null,
+  "banner": null,
   "roles": [],
   "joined_at": "2015-04-26T06:26:56.936000+00:00",
   "deaf": false,

docs/topics/Gateway_Events.md

@@ -714,6 +714,7 @@ Sent when a guild member is updated. This will also fire when the user object of
 | user                          | a [user](#DOCS_RESOURCES_USER/user-object) object                             | User                                                                                                                                                                                                                                 |
 | nick?                         | ?string                                                                       | Nickname of the user in the guild                                                                                                                                                                                                    |
 | avatar                        | ?string                                                                       | Member's [guild avatar hash](#DOCS_REFERENCE/image-formatting)                                                                                                                                                                       |
+| banner                        | ?string                                                                       | Member's [guild banner hash](#DOCS_REFERENCE/image-formatting)                                                                                                                                                                       |
 | joined_at                     | ?ISO8601 timestamp                                                            | When the user joined the guild                                                                                                                                                                                                       |
 | premium_since?                | ?ISO8601 timestamp                                                            | When the user starting [boosting](https://support.discord.com/hc/en-us/articles/360028038352-Server-Boosting-) the guild                                                                                                             |
 | deaf?                         | boolean                                                                       | Whether the user is deafened in voice channels                                                                                                                                                                                       |