[x/blog] go.blog: fix image in stathat article
[x/blog] go.blog: fix image in stathat article

Fixes golang/go#6904.

R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/39210043
X-Blog-Commit: d67810e6e4ff1c7bcde714ff7267f9f0006e06eb

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website