Announcement feature is used to display a message on top of the chabots for any important message to be displayed to the user or for promoting any seasonal sales or offers the company has.
Enabling the Announcement Feature
To add the Announcement feature, open the chatbot for which you want to add the Announcement and click on settings tab, click on Announcement tab which should look like this 
Click on Add Announcement and it opens a tab where you need to add the title and description of the announcement which should look like this.
Make sure that the Start Date and End Date are entered appropriately matching the time when you want the announcement to be displayed on the chatbot(s) along with the description and title for the announcement you create and click on submit which creates an announcement which can be used on the chatbots.
Note: When you click on the pencil Icon to edit the Announcement and if you made changes to any announcement, the toggle bar for Active goes inactive, make sure that you change it back to active after if any changes are made to an existing announcement.
Once the above steps are performed, you can click on test on the top of the chatbot page to test the chatbot created for the announcement feature added and this is how it should look 