x/tools/cmd/godoc: fix bad repository path
x/tools/cmd/godoc: fix bad repository path

Not caught by inattentive reviewer. Pick up your game, people.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/180880043

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