types2, go/types: remove doc link from Func.Pkg comment
The documentation link only works with exported identifiers. Further,
the built-in error interface lives in pseudo package "builtin" only,
thus it's not a real package that can be referred using doc links.
Change-Id: I2116beb27fc73ba33f8352301fe77b4b6abc3ec1
Reviewed-on: https://go-review.googlesource.com/c/go/+/534436 Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Alan Donovan <adonovan@google.com>