Use docker scout command Fixes #394

[patest-dev]

Update the security scanning section of the tutorial to use the docker scout command as docker scan was removed with the recent Docker Desktop 4.19.0 release.

I kept the wording related to Snyk, as I guess that still holds?

[jai-dewani]

This would also fix #416

I think using docker scout quickview getting-started would be a better command as it shows a compact precise version of cves. Also we will need to updated the sample output with the new scout command.

CC: @mikesir87