Update docs for new Container Tools extension

[bwateratmsft]

PLEASE DO NOT MERGE YET.

This is a large PR so I wanted to get it opened ASAP, to give more time to review. We plan to release Container Tools in the coming weeks.

The images I changed should be more-or-less drop-in replacements for the previous images. There are quite a few of them.

/cc @fiveisprime @ghogen

[ntrogh]

@bwateratmsft Should traffic to docker.md be redirected to containers.md? Can you also update the toc.json file to update the table of contents?

[bwateratmsft]

@bwateratmsft Should traffic to docker.md be redirected to containers.md? Can you also update the toc.json file to update the table of contents?

@ntrogh Yes, we would want that redirect. I updated toc.json to point to the new containers.md file, but I'm not sure what to do to redirect from docker.md to containers.md.

[ntrogh]

@bwateratmsft Redirects are managed in another repo. I'll take care of that once we have this PR merged.