docs(hooks): add info about belongs-to-many (#11601)

docs/manual/hooks.md

@@ -332,7 +332,8 @@ User.beforeBulkCreate((users, options) => {
 For the most part hooks will work the same for instances when being associated except a few things
 
 1. When using add/set functions the beforeUpdate/afterUpdate hooks will run.
-2. The only way to call beforeDestroy/afterDestroy hooks are on associations with `onDelete: 'cascade'` and the option `hooks: true`. For instance:
+2. When using add functions for belongsToMany relationships that will add record to pivot table, beforeBulkCreate/afterBulkCreate hooks in intermediate model will run.
+3. The only way to call beforeDestroy/afterDestroy hooks are on associations with `onDelete: 'cascade'` and the option `hooks: true`. For instance:
 
 ```js
 class Projects extends Model {}