lifecycle: Don't require /run/opencontainer/<runtime>/containers

[wking]

As discussed in #231. We already require it for
Linux/Unix-based systems, so we don't have to repeat it here. And
other systems will use different paths, which we haven't specified
yet. When I asked why we didn't specify a path for Windows,
Vincent said we were waiting on help from PoC implementations.
So this commit punts the location to the “State” section, and lets the
“Lifecycle” section just focus on when the write-to-filesystem
happens.

There's also discussion about removing the filesystem state registry
completely, in which case we'd want to remove the whole line from
the lifecycle. If we expect to switch to something like --state PATH in the near future this PR is just polishing dead
documentation.

[mrunalp]

LGTM

[duglin]

I'd prefer to NOT do this because we're replacing a concrete, and interoperable, solution with something that is not. If we don't like the current proposal then I think it would be better to only remove it when there's a viable alternative proposed - replace it with just "write it to the filesystem" doesn't help interop.

[wking]

On Mon, Dec 14, 2015 at 09:51:11AM -0800, Doug Davis wrote:

I'd prefer to NOT do this because we're replacing a concrete, and
interoperable, solution with something that is not…

This PR doesn't change the semantics for Linux/Unix-based systems,
which still require runtimes to write the state to
/run/opencontainer//containers based on wording in the
“State” section 1. It just removes the unqualified reference from
the “Lifecycle” section [2], which was redundant for Linux/Unix-based
systems and wrong for other systems.

[wking]

I just pushed 5402c1c → f89cb85 to fix a “commpletely” → “completely” typo in the commit message.

[duglin]

@wking ah, doi - sorry missed that. I take back my concerns :-)

[hqhq]

LGTM