dockerbuilder is missing from the object storage docs

[arschles]

Dockerbuilder uses object storage, so it should be added to https://github.com/deis/workflow/blob/master/src/installing-workflow/configuring-object-storage.md#credentials

[smothiki]

@arschles Can you be more specific about docs. I don't think dockerfile builder requires any additional docs

[arschles]

@smothiki you're right, closing

In case you're interested, this issue was opened when there was an exhaustive list of all the workflow components that used object storage, and the dockerbuilder component wasn't in the list. Now that such a list doesn't exist, and the dockerbuilder is mentioned under "Component Details", this issue is obsolete.