Docs fix: correct /commit info

Correct documentation for POST /commit to reflect that the container's
configuration is supplied in the request body, and not as a query
parameter.

Also correct a small typo in the example JSON for create container.

Docker-DCO-1.1-Signed-off-by: Andy Goldstein <agoldste@redhat.com> (github: ncdc)
Merge pull request #5443 from ncdc/commit-api-doc-fix

Docs fix: correct /commit info