doc: update security release process

[sam-github]

Checklist

• documentation is changed or added
• commit message follows commit guidelines

[sam-github]

@nodejs/docker Updating docker is a moderately complex process, and has been done by the docker team for the last two sec releases (rather than me, thanks!). Example: nodejs/docker-node#1209

I formalized this here. I added a step to open an issue in docker-node to notify the team of the upcoming sec release, the issue can then be closed when you PR the update. But perhaps I can remove those two steps, since you already watch the sec release announcement list, and you were already doing the integration by the time I got to the repo to kick off the process?

EDIT - also, I deleted a bunch of docker release process instructions, assuming that your team doesn't need them because its what you do all the time, but correct me if I'm wrong and those docs do need to go somewhere.

[mhdawson]

LGTM

[mhdawson]

Doc, only so not CI run required, only passing Travis job which is green. Landing.

[mhdawson]

Landed in f7771ff