Put := and <> methods in Connect ScalaDoc group

This puts Data's connection methods, `:=` and `<>`, in the ScalaDoc
`Connect` group. These groups will propagate through to all children of
Data, e.g., UInt, and cause those methods to be grouped in the ScalaDoc of
these children.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>