Exported Interface method docs should follow same rules as other exported identifiers

[jimmyfrasche]

Given

type Interface interface {
    //I don't mention the name.
    F()
}

I would expect

comment on exported interface method  F should be of the form "F ..."

Currently no warning is emitted.

[dsymonds]

That's not a style rule that is commonly followed, mainly because the comments aren't extracted by godoc. Same goes for struct fields.