2.xx.xx Documentation missing

[XenHat]

As pointed out in #179 (this comment specifically), some changes applied to the source code, especially the API, have not been documented. In my particular case, I spent the better part of an hour figuring out how to use the DefaultValue parameter in 2.xx.xx due to a rename to Default. The documentation for this seems to be entirely missing for the new API format, which can lead to pretty hairy migration issues.

Note: I am aware that 2.xx.xx is not ready for public consumption, I am simply trying to help the documentation effort and save some time for the next person who runs into my issue.

Also possibly related to #448