Function createAnnouncement

createAnnouncement(this, channel, user_targets, message): Promise<Channel>
Create a new announcement!
Parameters
- this: API
- channel: {
  description: string;
  name: string;
  }
  Details of the channel you're creating
  - description: string
  - name: string
- user_targets: (number | User)[]
  The people that will receive your message
- message: string
  The message to send with the announcement
Returns Promise<Channel>
The newly created channel!

Scope
"chat.write_manage"

Remarks
From my understanding, this WILL 403 unless the user is kinda special
- Defined in Chat.ts:101