Add vish to contributors.
Add vish to contributors.

R=r, rsc
http://go/go-review/1026012

Committer: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go