Prerequisites
A: User must be logged in.

1. Go to Release info page by clicking on a release label at top-left corner.

2. On the next page (Release info page), select a release label from the Label column in Release History table list.

3. Click on "Reason for Release " button.

4. In pop-up window, give reason(s) and click SUBMIT to finish.

See also
Make Release Official, Give Reason for This Version