Fix typo on architecture diagram. (#4109)
Fix typo on architecture diagram. (#4109)

Signed-off-by: Rigs Caballero <2974468a19f6df5f3e888d219e58465250b0dd68@google.com>
istio/istio.io,istio/istio.io,istio/istio.io,istio/istio.io,istio/istio.io,istio/istio.io,istio/istio.io