Add screenshots to features in features.yml.
Closes https://gitlab.com/gitlab-com/www-gitlab-com/issues/1605
Artboards w 1235 px x h 822.85 px
Notes:
- created this https://gitlab.com/gitlab-org/gitlab-ce/issues/36766 to fix the commit page dropdown menu, but already fixed on the screenshot added here.
- this branch was created from release-9-5 (https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/6668) to avoid conflicts, so the release post should be merged before this MR.