Correct how docker registry credentials are passed or documented

[RickMoynihan]

The docstring states credentials should be supplied like this:

pack.alpha/src/juxt/pack/api.clj

Lines 23 to 25 in 9fd4a63

	Credentials
	:from-registry - map of :username and :password to string, used for pulling from registry
	:to-registry - map of :username and :password to string, used for uploading to registry

However the opts on that api function are just passed directly into the jib namespace; and that expects the keys to be formatted like they are here:

pack.alpha/src/juxt/pack/jib.clj

Lines 163 to 164 in 9fd4a63

	to-registry-username
	to-registry-password

I'm happy to work up a patch for this; but it's unclear to me what the intention is.

A work around to pass to credentials is to just call api/docker with :to-registry-username and :to-registry-password set.

[SevereOverfl0w]

The documentation is correct, the code is wrong.