go.blog: fix typo in gophercon article
go.blog: fix typo in gophercon article

LGTM=mikioh.mikioh
R=golang-codereviews, mikioh.mikioh
CC=golang-codereviews
https://codereview.appspot.com/102840044

d0f/go-zh.blog,d0f/go-zh.blog,webfd/go-zh.blog,bryanxu/go-zh.blog,bryanxu/go-zh.blog,webfd/go-zh.blog