feat: added group_admin_changed event (#2018)

* docs: updated

* added group-admin-change event

* minor changes

* added usage example

* minor changes: code docs updated

index.d.ts

@@ -198,6 +198,12 @@ declare namespace WAWebJS {
             notification: GroupNotification
         ) => void): this
 
+        /** Emitted when a current user is promoted to an admin or demoted to a regular user */
+        on(event: 'group_admin_changed', listener: (
+            /** GroupNotification with more information about the action */
+            notification: GroupNotification
+        ) => void): this
+
         /** Emitted when group settings are updated, such as subject, description or picture */
         on(event: 'group_update', listener: (
             /** GroupNotification with more information about the action */
@@ -512,6 +518,7 @@ declare namespace WAWebJS {
         MEDIA_UPLOADED = 'media_uploaded',
         GROUP_JOIN = 'group_join',
         GROUP_LEAVE = 'group_leave',
+        GROUP_ADMIN_CHANGED = 'group_admin_changed',
         GROUP_UPDATE = 'group_update',
         QR_RECEIVED = 'qr',
         LOADING_SCREEN = 'loading_screen',