fix download url (#519)
fix download url (#519)

* fix download url

* remove "stable"

istio/istio.io,istio/istio.io,geeknoid/istio.github.io,geeknoid/istio.github.io,ZackButcher/istio.github.io,istio/istio.io,istio/istio.io,ZackButcher/istio.github.io,geeknoid/istio.github.io,smawson/istio.github.io,ZackButcher/istio.github.io,linsun/istio.github.io,geeknoid/istio.github.io,istio/istio.io,smawson/istio.github.io,ZackButcher/istio.github.io,linsun/istio.github.io,linsun/istio.github.io,linsun/istio.github.io,smawson/istio.github.io,jasminejaksic/istio.github.io,smawson/istio.github.io,jasminejaksic/istio.github.io,linsun/istio.github.io,jasminejaksic/istio.github.io,geeknoid/istio.github.io,istio/istio.io,istio/istio.io,jasminejaksic/istio.github.io