type alias in std lib - godoc alias struct

[Daniel Theophanes]

There are a few mirrored types in database/sql and database/sql/driver. It isn't huge, but I could unify these duplicate in this release cycle if use of alias in the stdlib is allowed in 1.9 [1].

Related to the above, currently type alias of a struct will just show the struct name, and not the fields in godoc. In the case of database/sql, it seems like this would be annoying to the user of the sql package. Would it be of value to show struct fields in godoc when the alias is to a struct? Without this I suspect it would tilt the scales to the side of leaving things as is, which would also be fine.

[1] https://go-review.googlesource.com/c/40474/