go.tools/go/types: correct a comment (was pointing at wrong issue)
go.tools/go/types: correct a comment (was pointing at wrong issue)

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/76160044

cmars/tools,argandas/tools,cw2018/tools,golang/tools,cw2018/tools,runcom/tools,cmars/tools,cw2018/tools,magiccao/tools,glasser/golang-tools,magiccao/tools,syreclabs/go-tools,nicot/tools,matryer/tools,nicot/tools,matryer/tools,argandas/tools,sshetty10/tools,springning/tools,jdhenke/tools,4ad/tools,maddyonline/tools,springning/tools,josharian/tools,dmitris/tools,josharian/tools,glasser/golang-tools,magiccao/tools,golang/tools,nicot/tools,springning/tools,argandas/tools,syreclabs/go-tools,nicot/tools,josharian/tools,syreclabs/go-tools,argandas/tools,runcom/tools,runcom/tools,cmars/tools,sshetty10/tools,syreclabs/go-tools,magiccao/tools,golang/tools,golang/tools,dmitris/tools,syreclabs/go-tools,maddyonline/tools,matryer/tools,4ad/tools,jdhenke/tools,maddyonline/tools,springning/tools,josharian/tools,maddyonline/tools,4ad/tools,cw2018/tools,syreclabs/go-tools,jdhenke/tools,sshetty10/tools,matryer/tools,runcom/tools,jdhenke/tools,glasser/golang-tools,cmars/tools,sshetty10/tools,golang/tools,glasser/golang-tools,dmitris/tools,dmitris/tools