edit: updated `Security scanning` section (#13546)
edit: updated `Security scanning` section (#13546)

* edit: updated `Security scanning` section

`docker scan` fails when user is not logged in to Docker Hub. First I had to use `docker login` to login to Docker Hub. Afterwards, `docker scan` worked.

* Update 09_image_best.md

Update format, fix a typo

Co-authored-by: Usha Mandya <63fc8324d194bb900191b7ad7215ea10fd135fb2@users.noreply.github.com>
thaJeztah/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,thaJeztah/docker.github.io