*: Move closer to project-template's current status

[wking]

Generated with:

$ git remote add project-template git://github.com/opencontainers/project-template.git
$ git fetch project-template
$ git show --oneline project-template/master
61d73a3 (project-template/master) Merge pull request #40 from wking/minor-patch-bullet
$ git merge --squash --allow-unrelated-histories project-template/master
$ git checkout HEAD -- .pullapprove.yml MAINTAINERS README.md RELEASES.md
$ git checkout project-template/master -- GOVERNANCE.md LICENSE
$ emacs README.md CONTRIBUTING.md # unify around project-template's CONTRIBUTING.md approach
$ emacs meeting.ics  # update link to point at CONTRIBUTING.md#meetings
$ git commit -sv

I personally prefer non-squash merges to preserve history and ease future updates, but that approach has not been popular within the OCI, so I'm going with a squash-merge here.

I'm sticking with the local RELEASES.md, because it uses four-space indents. I've filed opencontainers/project-template#54 to upstream that change.

I've also filed opencontainers/project-template#55 upstreaming our local wording change from #943.

I've also fixed the GOVERNANCE.md security link in flight with opencontainers/project-template#34.

I've left the other in-flight project-template changes alone.

I've wrapped the URL in meetings.ics to avoid:

Line length should not be longer than 75 characters near line #33
Reference: RFC 5545 3.1. Content Lines

[wking]

There was a previous run at something similar in #420, which was closed because the template docs were, at that time, not sufficiently generic. With opencontainers/project-template#20 having landed since (via a bunch of separate PRs), I think it's worth taking another stab at this ;).

[vbatts]

house keeping: bugger. I'm sure these are good changes, but with much of this being pointed at https://github.com/opencontainers/org I think this PR would have to be completely redone