api: docs: remove deprecated RootFS.BaseLayer (current API version)
This field was used when Windows did not yet support regular images, and required
the base-image to pre-exist on the Windows machine (as those layers were not yet
allowed to be distributed).
Commit f342b27145d8f5af27cd5de1501551af275e899b (docker 1.13.0, API v1.25) removed
usage of the field. The field was not documented in the API, but because it was not
removed from the Golang structs in the API, ended up in the API documentation when
we switched to using Swagger instead of plain MarkDown for the API docs.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Sebastiaan van Stijn