This is an extension of #14004, but applied to constants and variables.

Currently I see:

$ go doc reflect | egrep "ChanDir|Kind"
const RecvDir ChanDir = 1 << iota ...
const Invalid Kind = iota ...
type ChanDir int
type Kind uint

I expect to see:

$ go doc reflect | egrep "ChanDir|Kind"
type ChanDir int
    const RecvDir ChanDir = 1 << iota ...
type Kind uint
    const Invalid Kind = iota ...

This would make the go doc tool more consistent with itself (we do groupiing for functions, but not variables and constants) and also with the display of godoc. More importantly, it makes the printout easier to parse by human eyes.

\cc @robpike, I can make the change in Go1.8, if you're okay with this.